21371520 has 64 divisors (see below), whose sum is σ = 68127840. Its totient is φ = 5698560.

The previous prime is 21371509. The next prime is 21371551. The reversal of 21371520 is 2517312.

It is a tau number, because it is divible by the number of its divisors (64).

It is a super-2 number, since 2×21371520² = 913483734220800, which contains 22 as substring.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 3646 + ... + 7485.

Almost surely, 2^21371520 is an apocalyptic number.

21371520 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21371520 is an abundant number, since it is smaller than the sum of its proper divisors (46756320).

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

21371520 is a wasteful number, since it uses less digits than its factorization.

21371520 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 11153 (or 11141 counting only the distinct ones).

The product of its (nonzero) digits is 420, while the sum is 21.

The square root of 21371520 is about 4622.9341332102. The cubic root of 21371520 is about 277.5098933247.

Adding to 21371520 its reverse (2517312), we get a palindrome (23888832).

The spelling of 21371520 in words is "twenty-one million, three hundred seventy-one thousand, five hundred twenty".