21928180 has 24 divisors (see below), whose sum is σ = 46149768. Its totient is φ = 8752128.

The previous prime is 21928171. The next prime is 21928189. The reversal of 21928180 is 8182912.

It is a happy number.

It is an interprime number because it is at equal distance from previous prime (21928171) and next prime (21928189).

It can be written as a sum of positive squares in 4 ways, for example, as 7056 + 21921124 = 84^2 + 4682^2 .

It is a super-2 number, since 2×21928180² = 961690156224800, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21928189) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 11452 + ... + 13228.

It is an arithmetic number, because the mean of its divisors is an integer number (1922907).

Almost surely, 2^21928180 is an apocalyptic number.

21928180 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21928180 is an abundant number, since it is smaller than the sum of its proper divisors (24221588).

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

21928180 is a wasteful number, since it uses less digits than its factorization.

21928180 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2403 (or 2401 counting only the distinct ones).

The product of its (nonzero) digits is 2304, while the sum is 31.

The square root of 21928180 is about 4682.7534635084. The cubic root of 21928180 is about 279.8986878365.

The spelling of 21928180 in words is "twenty-one million, nine hundred twenty-eight thousand, one hundred eighty".