21958980 has 24 divisors (see below), whose sum is σ = 61485312. Its totient is φ = 5855712.

The previous prime is 21958973. The next prime is 21958987. The reversal of 21958980 is 8985912.

It is a happy number.

It is an interprime number because it is at equal distance from previous prime (21958973) and next prime (21958987).

It is not an unprimeable number, because it can be changed into a prime (21958987) 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, 182932 + ... + 183051.

It is an arithmetic number, because the mean of its divisors is an integer number (2561888).

Almost surely, 2^21958980 is an apocalyptic number.

21958980 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21958980 is an abundant number, since it is smaller than the sum of its proper divisors (39526332).

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

21958980 is a wasteful number, since it uses less digits than its factorization.

21958980 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 365995 (or 365993 counting only the distinct ones).

The product of its (nonzero) digits is 51840, while the sum is 42.

The square root of 21958980 is about 4686.0409729323. The cubic root of 21958980 is about 280.0296737259.

It can be divided in two parts, 2195 and 8980, that added together give a triangular number (11175 = T₁₄₉).

The spelling of 21958980 in words is "twenty-one million, nine hundred fifty-eight thousand, nine hundred eighty".