21561190 has 16 divisors (see below), whose sum is σ = 44354592. Its totient is φ = 7392384.

The previous prime is 21561179. The next prime is 21561193. The reversal of 21561190 is 9116512.

It is a super-2 number, since 2×21561190² = 929769828432200, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21561193) 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, 153939 + ... + 154078.

It is an arithmetic number, because the mean of its divisors is an integer number (2772162).

Almost surely, 2^21561190 is an apocalyptic number.

21561190 is an abundant number, since it is smaller than the sum of its proper divisors (22793402).

21561190 is a wasteful number, since it uses less digits than its factorization.

21561190 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 308031.

The product of its (nonzero) digits is 540, while the sum is 25.

The square root of 21561190 is about 4643.4028470509. The cubic root of 21561190 is about 278.3284336650.

The spelling of 21561190 in words is "twenty-one million, five hundred sixty-one thousand, one hundred ninety".