21256706 has 16 divisors (see below), whose sum is σ = 34346400. Its totient is φ = 9834048.

The previous prime is 21256693. The next prime is 21256709. The reversal of 21256706 is 60765212.

It is not an unprimeable number, because it can be changed into a prime (21256709) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 4871 + ... + 8138.

It is an arithmetic number, because the mean of its divisors is an integer number (2146650).

Almost surely, 2^21256706 is an apocalyptic number.

21256706 is a deficient number, since it is larger than the sum of its proper divisors (13089694).

21256706 is a wasteful number, since it uses less digits than its factorization.

21256706 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 13073.

The product of its (nonzero) digits is 5040, while the sum is 29.

The square root of 21256706 is about 4610.4995390955. The cubic root of 21256706 is about 277.0120462034.

The spelling of 21256706 in words is "twenty-one million, two hundred fifty-six thousand, seven hundred six".