21945580 has 24 divisors (see below), whose sum is σ = 46267200. Its totient is φ = 8743680.

The previous prime is 21945577. The next prime is 21945587. The reversal of 21945580 is 8554912.

It is a hoax number, since the sum of its digits (34) coincides with the sum of the digits of its distinct prime factors.

It is not an unprimeable number, because it can be changed into a prime (21945587) 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, 3396 + ... + 7444.

It is an arithmetic number, because the mean of its divisors is an integer number (1927800).

Almost surely, 2^21945580 is an apocalyptic number.

21945580 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21945580 is an abundant number, since it is smaller than the sum of its proper divisors (24321620).

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

21945580 is a wasteful number, since it uses less digits than its factorization.

21945580 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4329 (or 4327 counting only the distinct ones).

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

The square root of 21945580 is about 4684.6109763779. The cubic root of 21945580 is about 279.9727014202.

The spelling of 21945580 in words is "twenty-one million, nine hundred forty-five thousand, five hundred eighty".