21512772 has 18 divisors (see below), whose sum is σ = 54379598. Its totient is φ = 7170912.

The previous prime is 21512767. The next prime is 21512783. The reversal of 21512772 is 27721512.

It can be written as a sum of positive squares in only one way, i.e., 21399876 + 112896 = 4626^2 + 336^2 .

It is a tau number, because it is divible by the number of its divisors (18).

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 298753 + ... + 298824.

Almost surely, 2^21512772 is an apocalyptic number.

It is an amenable number.

21512772 is an abundant number, since it is smaller than the sum of its proper divisors (32866826).

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

21512772 is a wasteful number, since it uses less digits than its factorization.

21512772 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 597587 (or 597582 counting only the distinct ones).

The product of its digits is 1960, while the sum is 27.

The square root of 21512772 is about 4638.1862834518. The cubic root of 21512772 is about 278.1199385857.

The spelling of 21512772 in words is "twenty-one million, five hundred twelve thousand, seven hundred seventy-two".