21713868 has 36 divisors (see below), whose sum is σ = 59878728. Its totient is φ = 6579840.

The previous prime is 21713849. The next prime is 21713873. The reversal of 21713868 is 86831712.

It is a tau number, because it is divible by the number of its divisors (36).

It is a Harshad number since it is a multiple of its sum of digits (36).

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 27021 + ... + 27812.

It is an arithmetic number, because the mean of its divisors is an integer number (1663298).

Almost surely, 2^21713868 is an apocalyptic number.

It is an amenable number.

21713868 is an abundant number, since it is smaller than the sum of its proper divisors (38164860).

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

21713868 is a wasteful number, since it uses less digits than its factorization.

21713868 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 54854 (or 54849 counting only the distinct ones).

The product of its digits is 16128, while the sum is 36.

The square root of 21713868 is about 4659.8141593845. The cubic root of 21713868 is about 278.9838507630.

The spelling of 21713868 in words is "twenty-one million, seven hundred thirteen thousand, eight hundred sixty-eight".