21790131 has 32 divisors (see below), whose sum is σ = 34836480. Its totient is φ = 11959200.

The previous prime is 21790127. The next prime is 21790157. The reversal of 21790131 is 13109712.

It is not a de Polignac number, because 21790131 - 2² = 21790127 is a prime.

It is a super-2 number, since 2×21790131² = 949619617994322, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (21790931) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 13666 + ... + 15176.

It is an arithmetic number, because the mean of its divisors is an integer number (1088640).

Almost surely, 2^21790131 is an apocalyptic number.

21790131 is a deficient number, since it is larger than the sum of its proper divisors (13046349).

21790131 is a wasteful number, since it uses less digits than its factorization.

21790131 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1567.

The product of its (nonzero) digits is 378, while the sum is 24.

The square root of 21790131 is about 4667.9900385498. The cubic root of 21790131 is about 279.3100829103.

Adding to 21790131 its reverse (13109712), we get a palindrome (34899843).

The spelling of 21790131 in words is "twenty-one million, seven hundred ninety thousand, one hundred thirty-one".