21645536 has 24 divisors (see below), whose sum is σ = 46489464. Its totient is φ = 9838720.

The previous prime is 21645527. The next prime is 21645551. The reversal of 21645536 is 63554612.

It is a Harshad number since it is a multiple of its sum of digits (32).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 30395 + ... + 31098.

It is an arithmetic number, because the mean of its divisors is an integer number (1937061).

Almost surely, 2^21645536 is an apocalyptic number.

It is an amenable number.

21645536 is an abundant number, since it is smaller than the sum of its proper divisors (24843928).

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

21645536 is a wasteful number, since it uses less digits than its factorization.

21645536 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 61514 (or 61506 counting only the distinct ones).

The product of its digits is 21600, while the sum is 32.

The square root of 21645536 is about 4652.4763298699. The cubic root of 21645536 is about 278.6908957920.

The spelling of 21645536 in words is "twenty-one million, six hundred forty-five thousand, five hundred thirty-six".