21256970 has 32 divisors (see below), whose sum is σ = 46303488. Its totient is φ = 6859008.

The previous prime is 21256931. The next prime is 21256997. The reversal of 21256970 is 7965212.

It is a Curzon number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 7742 + ... + 10121.

It is an arithmetic number, because the mean of its divisors is an integer number (1446984).

Almost surely, 2^21256970 is an apocalyptic number.

21256970 is an abundant number, since it is smaller than the sum of its proper divisors (25046518).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21256970 is a wasteful number, since it uses less digits than its factorization.

21256970 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 17894.

The product of its (nonzero) digits is 7560, while the sum is 32.

The square root of 21256970 is about 4610.5281693099. The cubic root of 21256970 is about 277.0131929925.

The spelling of 21256970 in words is "twenty-one million, two hundred fifty-six thousand, nine hundred seventy".