21386500 has 24 divisors (see below), whose sum is σ = 46709208. Its totient is φ = 8554400.

The previous prime is 21386489. The next prime is 21386501. The reversal of 21386500 is 568312.

It is a happy number.

It can be written as a sum of positive squares in 4 ways, for example, as 4064256 + 17322244 = 2016^2 + 4162^2 .

It is a Harshad number since it is a multiple of its sum of digits (25).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21386501) 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, 20887 + ... + 21886.

It is an arithmetic number, because the mean of its divisors is an integer number (1946217).

Almost surely, 2^21386500 is an apocalyptic number.

21386500 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21386500 is an abundant number, since it is smaller than the sum of its proper divisors (25322708).

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

21386500 is a wasteful number, since it uses less digits than its factorization.

21386500 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 42792 (or 42780 counting only the distinct ones).

The product of its (nonzero) digits is 1440, while the sum is 25.

The square root of 21386500 is about 4624.5540325528. The cubic root of 21386500 is about 277.5747167798.

It can be divided in two parts, 21386 and 500, that multiplied together give a triangular number (10693000 = T₄₆₂₄).

The spelling of 21386500 in words is "twenty-one million, three hundred eighty-six thousand, five hundred".