21400860 has 48 divisors (see below), whose sum is σ = 64534176. Its totient is φ = 5267712.

The previous prime is 21400849. The next prime is 21400877. The reversal of 21400860 is 6800412.

It is a congruent number.

It is an unprimeable number.

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 15 ways as a sum of consecutive naturals, for example, 12939 + ... + 14498.

It is an arithmetic number, because the mean of its divisors is an integer number (1344462).

Almost surely, 2^21400860 is an apocalyptic number.

21400860 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21400860 is an abundant number, since it is smaller than the sum of its proper divisors (43133316).

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

21400860 is a wasteful number, since it uses less digits than its factorization.

21400860 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 27462 (or 27460 counting only the distinct ones).

The product of its (nonzero) digits is 384, while the sum is 21.

The square root of 21400860 is about 4626.1063541601. The cubic root of 21400860 is about 277.6368288775.

The spelling of 21400860 in words is "twenty-one million, four hundred thousand, eight hundred sixty".