21386560 has 112 divisors (see below), whose sum is σ = 56455056. Its totient is φ = 7667712.

The previous prime is 21386557. The next prime is 21386567. The reversal of 21386560 is 6568312.

It can be written as a sum of positive squares in 8 ways, for example, as 665856 + 20720704 = 816^2 + 4552^2 .

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21386567) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 220432 + ... + 220528.

It is an arithmetic number, because the mean of its divisors is an integer number (504063).

Almost surely, 2^21386560 is an apocalyptic number.

21386560 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21386560, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (28227528).

21386560 is an abundant number, since it is smaller than the sum of its proper divisors (35068496).

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

21386560 is a wasteful number, since it uses less digits than its factorization.

21386560 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 180 (or 170 counting only the distinct ones).

The product of its (nonzero) digits is 8640, while the sum is 31.

The square root of 21386560 is about 4624.5605196602. The cubic root of 21386560 is about 277.5749763589.

The spelling of 21386560 in words is "twenty-one million, three hundred eighty-six thousand, five hundred sixty".