21072996 has 72 divisors (see below), whose sum is σ = 64471680. Its totient is φ = 5665536.

The previous prime is 21072973. The next prime is 21073001. The reversal of 21072996 is 69927012.

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a self number, because there is not a number n which added to its sum of digits gives 21072996.

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 1825 + ... + 6743.

It is an arithmetic number, because the mean of its divisors is an integer number (895440).

Almost surely, 2^21072996 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 21072996, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (32235840).

21072996 is an abundant number, since it is smaller than the sum of its proper divisors (43398684).

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

21072996 is a wasteful number, since it uses less digits than its factorization.

21072996 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4953 (or 4948 counting only the distinct ones).

The product of its (nonzero) digits is 13608, while the sum is 36.

The square root of 21072996 is about 4590.5333023517. The cubic root of 21072996 is about 276.2117153117.

The spelling of 21072996 in words is "twenty-one million, seventy-two thousand, nine hundred ninety-six".