21386790 has 24 divisors (see below), whose sum is σ = 55605888. Its totient is φ = 5703120.

The previous prime is 21386773. The next prime is 21386791. The reversal of 21386790 is 9768312.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21386791) 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 11 ways as a sum of consecutive naturals, for example, 118726 + ... + 118905.

It is an arithmetic number, because the mean of its divisors is an integer number (2316912).

Almost surely, 2^21386790 is an apocalyptic number.

21386790 is an abundant number, since it is smaller than the sum of its proper divisors (34219098).

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

21386790 is a wasteful number, since it uses less digits than its factorization.

21386790 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 237644 (or 237641 counting only the distinct ones).

The product of its (nonzero) digits is 18144, while the sum is 36.

The square root of 21386790 is about 4624.5853868212. The cubic root of 21386790 is about 277.5759714078.

The spelling of 21386790 in words is "twenty-one million, three hundred eighty-six thousand, seven hundred ninety".