21207956 has 48 divisors (see below), whose sum is σ = 47548032. Its totient is φ = 8035200.

The previous prime is 21207881. The next prime is 21207997. The reversal of 21207956 is 65970212.

It is a congruent 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, 10466 + ... + 12326.

It is an arithmetic number, because the mean of its divisors is an integer number (990584).

Almost surely, 2^21207956 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21207956, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (23774016).

21207956 is an abundant number, since it is smaller than the sum of its proper divisors (26340076).

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

21207956 is a wasteful number, since it uses less digits than its factorization.

21207956 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1920 (or 1918 counting only the distinct ones).

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

The square root of 21207956 is about 4605.2096586366. The cubic root of 21207956 is about 276.8001181963.

The spelling of 21207956 in words is "twenty-one million, two hundred seven thousand, nine hundred fifty-six".