21064540 has 48 divisors (see below), whose sum is σ = 53222400. Its totient is φ = 6841152.

The previous prime is 21064523. The next prime is 21064553. The reversal of 21064540 is 4546012.

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, 1300 + ... + 6619.

It is an arithmetic number, because the mean of its divisors is an integer number (1108800).

Almost surely, 2^21064540 is an apocalyptic number.

21064540 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21064540 is an abundant number, since it is smaller than the sum of its proper divisors (32157860).

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

21064540 is a wasteful number, since it uses less digits than its factorization.

21064540 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7954 (or 7952 counting only the distinct ones).

The product of its (nonzero) digits is 960, while the sum is 22.

The square root of 21064540 is about 4589.6121840522. The cubic root of 21064540 is about 276.1747650406.

The spelling of 21064540 in words is "twenty-one million, sixty-four thousand, five hundred forty".