21523612 has 24 divisors (see below), whose sum is σ = 41659632. Its totient is φ = 9648000.

The previous prime is 21523609. The next prime is 21523631. The reversal of 21523612 is 21632512.

It is a Harshad number since it is a multiple of its sum of digits (22).

It is a congruent number.

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, 139 + ... + 6562.

It is an arithmetic number, because the mean of its divisors is an integer number (1735818).

Almost surely, 2^21523612 is an apocalyptic number.

21523612 is a gapful number since it is divisible by the number (22) formed by its first and last digit.

It is an amenable number.

21523612 is a deficient number, since it is larger than the sum of its proper divisors (20136020).

21523612 is a wasteful number, since it uses less digits than its factorization.

21523612 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6789 (or 6787 counting only the distinct ones).

The product of its digits is 720, while the sum is 22.

The square root of 21523612 is about 4639.3546965068. The cubic root of 21523612 is about 278.1666443891.

Subtracting 21523612 from its reverse (21632512), we obtain a square (108900 = 330²).

The spelling of 21523612 in words is "twenty-one million, five hundred twenty-three thousand, six hundred twelve".