Pixlr Express (by Autodesk) is a good all-in-one photo processing app which includes Denoise as well as blur, sharpen, red eye, touch up, crop, rotate, colour, vibrance, contrast, etc, etc. Plus a crop of effects, text overlays, borders, etc.
However, Photoshop Touch not only has most of what you'd need to process photos (e.g. curves, levels, shadows/highlights, colour balance, reduce noise), it also allows you to use layers and masking as in CS or Elements.
Pixlr Express is free, PS Touch is £6.99 but worth it if you're serious about processing on a phone or tablet.