21072956 has 24 divisors (see below), whose sum is σ = 37537920. Its totient is φ = 10350000.

The previous prime is 21072923. The next prime is 21072973. The reversal of 21072956 is 65927012.

It is a Smith number, since the sum of its digits (32) coincides with the sum of the digits of its prime factors.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 83831 + ... + 84081.

It is an arithmetic number, because the mean of its divisors is an integer number (1564080).

Almost surely, 2^21072956 is an apocalyptic number.

It is an amenable number.

21072956 is a deficient number, since it is larger than the sum of its proper divisors (16464964).

21072956 is a wasteful number, since it uses less digits than its factorization.

21072956 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 545 (or 543 counting only the distinct ones).

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

The square root of 21072956 is about 4590.5289455574. The cubic root of 21072956 is about 276.2115405466.

Adding to 21072956 its reverse (65927012), we get a palindrome (86999968).

The spelling of 21072956 in words is "twenty-one million, seventy-two thousand, nine hundred fifty-six".