21512928 has 48 divisors (see below), whose sum is σ = 56745360. Its totient is φ = 7136256.

The previous prime is 21512917. The next prime is 21512941. The reversal of 21512928 is 82921512.

It is a tau number, because it is divible by the number of its divisors (48).

It is a super-2 number, since 2×21512928² = 925612142266368, which contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 21512895 and 21512904.

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, 26188 + ... + 26996.

It is an arithmetic number, because the mean of its divisors is an integer number (1182195).

Almost surely, 2^21512928 is an apocalyptic number.

It is an amenable number.

21512928 is an abundant number, since it is smaller than the sum of its proper divisors (35232432).

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

21512928 is a wasteful number, since it uses less digits than its factorization.

21512928 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1099 (or 1091 counting only the distinct ones).

The product of its digits is 2880, while the sum is 30.

The square root of 21512928 is about 4638.2031003396. The cubic root of 21512928 is about 278.1206108469.

It can be divided in two parts, 2 and 1512928, that added together give a triangular number (1512930 = T₁₇₃₉).

The spelling of 21512928 in words is "twenty-one million, five hundred twelve thousand, nine hundred twenty-eight".