21722180 has 24 divisors (see below), whose sum is σ = 46090968. Its totient is φ = 8598528.

The previous prime is 21722167. The next prime is 21722201. The reversal of 21722180 is 8122712.

It can be written as a sum of positive squares in 4 ways, for example, as 506944 + 21215236 = 712^2 + 4606^2 .

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 3659 + ... + 7538.

It is an arithmetic number, because the mean of its divisors is an integer number (1920457).

Almost surely, 2^21722180 is an apocalyptic number.

21722180 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21722180 is an abundant number, since it is smaller than the sum of its proper divisors (24368788).

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

21722180 is a wasteful number, since it uses less digits than its factorization.

21722180 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 11303 (or 11301 counting only the distinct ones).

The product of its (nonzero) digits is 448, while the sum is 23.

The square root of 21722180 is about 4660.7059551102. The cubic root of 21722180 is about 279.0194442669.

Adding to 21722180 its reverse (8122712), we get a palindrome (29844892).

The spelling of 21722180 in words is "twenty-one million, seven hundred twenty-two thousand, one hundred eighty".