21023916 has 12 divisors (see below), whose sum is σ = 49055832. Its totient is φ = 7007968.

The previous prime is 21023887. The next prime is 21023923. The reversal of 21023916 is 61932012.

It is a tau number, because it is divible by the number of its divisors (12).

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, 875985 + ... + 876008.

It is an arithmetic number, because the mean of its divisors is an integer number (4087986).

Almost surely, 2^21023916 is an apocalyptic number.

It is an amenable number.

21023916 is an abundant number, since it is smaller than the sum of its proper divisors (28031916).

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

21023916 is a wasteful number, since it uses less digits than its factorization.

21023916 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1752000 (or 1751998 counting only the distinct ones).

The product of its (nonzero) digits is 648, while the sum is 24.

The square root of 21023916 is about 4585.1844019625. The cubic root of 21023916 is about 275.9971119210.

Adding to 21023916 its reverse (61932012), we get a palindrome (82955928).

The spelling of 21023916 in words is "twenty-one million, twenty-three thousand, nine hundred sixteen".