21915180 has 72 divisors (see below), whose sum is σ = 75976992. Its totient is φ = 5008896.

The previous prime is 21915169. The next prime is 21915181. The reversal of 21915180 is 8151912.

It is a super-2 number, since 2×21915180² = 960550228864800, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (21915181) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 7437 + ... + 9956.

It is an arithmetic number, because the mean of its divisors is an integer number (1055236).

Almost surely, 2^21915180 is an apocalyptic number.

21915180 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21915180 is an abundant number, since it is smaller than the sum of its proper divisors (54061812).

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

21915180 is a wasteful number, since it uses less digits than its factorization.

21915180 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 17415 (or 17410 counting only the distinct ones).

The product of its (nonzero) digits is 720, while the sum is 27.

The square root of 21915180 is about 4681.3651854988. The cubic root of 21915180 is about 279.8433647737.

The spelling of 21915180 in words is "twenty-one million, nine hundred fifteen thousand, one hundred eighty".