21386406 has 16 divisors (see below), whose sum is σ = 43315200. Its totient is φ = 7038408.

The previous prime is 21386399. The next prime is 21386429. The reversal of 21386406 is 60468312.

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 7 ways as a sum of consecutive naturals, for example, 22086 + ... + 23033.

It is an arithmetic number, because the mean of its divisors is an integer number (2707200).

Almost surely, 2^21386406 is an apocalyptic number.

21386406 is an abundant number, since it is smaller than the sum of its proper divisors (21928794).

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

21386406 is a wasteful number, since it uses less digits than its factorization.

21386406 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 45203.

The product of its (nonzero) digits is 6912, while the sum is 30.

The square root of 21386406 is about 4624.5438693994. The cubic root of 21386406 is about 277.5743101048.

The spelling of 21386406 in words is "twenty-one million, three hundred eighty-six thousand, four hundred six".