21538536 has 32 divisors (see below), whose sum is σ = 54375360. Its totient is φ = 7108992.

The previous prime is 21538523. The next prime is 21538547. The reversal of 21538536 is 63583512.

It is a junction number, because it is equal to n+sod(n) for n = 21538497 and 21538506.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1885 + ... + 6828.

It is an arithmetic number, because the mean of its divisors is an integer number (1699230).

Almost surely, 2^21538536 is an apocalyptic number.

It is an amenable number.

21538536 is an abundant number, since it is smaller than the sum of its proper divisors (32836824).

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

21538536 is a wasteful number, since it uses less digits than its factorization.

21538536 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 8825 (or 8821 counting only the distinct ones).

The product of its digits is 21600, while the sum is 33.

The square root of 21538536 is about 4640.9628311375. The cubic root of 21538536 is about 278.2309210833.

The spelling of 21538536 in words is "twenty-one million, five hundred thirty-eight thousand, five hundred thirty-six".