21273864 has 32 divisors (see below), whose sum is σ = 53449440. Its totient is φ = 7056000.

The previous prime is 21273841. The next prime is 21273869. The reversal of 21273864 is 46837212.

It is not an unprimeable number, because it can be changed into a prime (21273869) 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, 2964 + ... + 7164.

It is an arithmetic number, because the mean of its divisors is an integer number (1670295).

Almost surely, 2^21273864 is an apocalyptic number.

21273864 is a gapful number since it is divisible by the number (24) formed by its first and last digit.

It is an amenable number.

21273864 is an abundant number, since it is smaller than the sum of its proper divisors (32175576).

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

21273864 is a wasteful number, since it uses less digits than its factorization.

21273864 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4421 (or 4417 counting only the distinct ones).

The product of its digits is 16128, while the sum is 33.

The square root of 21273864 is about 4612.3599165720. The cubic root of 21273864 is about 277.0865590720.

The spelling of 21273864 in words is "twenty-one million, two hundred seventy-three thousand, eight hundred sixty-four".