21373520 has 40 divisors (see below), whose sum is σ = 56793984. Its totient is φ = 7327872.

The previous prime is 21373511. The next prime is 21373523. The reversal of 21373520 is 2537312.

It is a tau number, because it is divible by the number of its divisors (40).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21373523) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 18524 + ... + 19643.

Almost surely, 2^21373520 is an apocalyptic number.

21373520 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21373520 is an abundant number, since it is smaller than the sum of its proper divisors (35420464).

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

21373520 is a wasteful number, since it uses less digits than its factorization.

21373520 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 38187 (or 38181 counting only the distinct ones).

The product of its (nonzero) digits is 1260, while the sum is 23.

The square root of 21373520 is about 4623.1504409872. The cubic root of 21373520 is about 277.5185497434.

The spelling of 21373520 in words is "twenty-one million, three hundred seventy-three thousand, five hundred twenty".