21455980 has 48 divisors (see below), whose sum is σ = 55460160. Its totient is φ = 6789888.

The previous prime is 21455977. The next prime is 21455983. The reversal of 21455980 is 8955412.

It is an interprime number because it is at equal distance from previous prime (21455977) and next prime (21455983).

It is not an unprimeable number, because it can be changed into a prime (21455983) 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, 4075 + ... + 7714.

It is an arithmetic number, because the mean of its divisors is an integer number (1155420).

Almost surely, 2^21455980 is an apocalyptic number.

21455980 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21455980 is an abundant number, since it is smaller than the sum of its proper divisors (34004180).

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

21455980 is a wasteful number, since it uses less digits than its factorization.

21455980 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 11818 (or 11816 counting only the distinct ones).

The product of its (nonzero) digits is 14400, while the sum is 34.

The square root of 21455980 is about 4632.0600168823. The cubic root of 21455980 is about 277.8749847641.

The spelling of 21455980 in words is "twenty-one million, four hundred fifty-five thousand, nine hundred eighty".