21358180 has 12 divisors (see below), whose sum is σ = 44852220. Its totient is φ = 8543264.

The previous prime is 21358159. The next prime is 21358187. The reversal of 21358180 is 8185312.

It can be written as a sum of positive squares in 2 ways, for example, as 5866084 + 15492096 = 2422^2 + 3936^2 .

It is not an unprimeable number, because it can be changed into a prime (21358187) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 533935 + ... + 533974.

It is an arithmetic number, because the mean of its divisors is an integer number (3737685).

Almost surely, 2^21358180 is an apocalyptic number.

21358180 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21358180 is an abundant number, since it is smaller than the sum of its proper divisors (23494040).

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

21358180 is a wasteful number, since it uses less digits than its factorization.

21358180 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1067918 (or 1067916 counting only the distinct ones).

The product of its (nonzero) digits is 1920, while the sum is 28.

The square root of 21358180 is about 4621.4911013654. The cubic root of 21358180 is about 277.4521411933.

The spelling of 21358180 in words is "twenty-one million, three hundred fifty-eight thousand, one hundred eighty".