21501868 has 12 divisors (see below), whose sum is σ = 37994320. Its totient is φ = 10646352.

The previous prime is 21501859. The next prime is 21501869. The reversal of 21501868 is 86810512.

It is a hoax number, since the sum of its digits (31) coincides with the sum of the digits of its distinct prime factors.

It is not an unprimeable number, because it can be changed into a prime (21501869) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 25683 + ... + 26506.

Almost surely, 2^21501868 is an apocalyptic number.

It is an amenable number.

21501868 is a deficient number, since it is larger than the sum of its proper divisors (16492452).

21501868 is a wasteful number, since it uses less digits than its factorization.

21501868 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 52296 (or 52294 counting only the distinct ones).

The product of its (nonzero) digits is 3840, while the sum is 31.

The square root of 21501868 is about 4637.0106749931. The cubic root of 21501868 is about 278.0729411969.

The spelling of 21501868 in words is "twenty-one million, five hundred one thousand, eight hundred sixty-eight".