21080931 has 8 divisors (see below), whose sum is σ = 28158144. Its totient is φ = 14028840.

The previous prime is 21080897. The next prime is 21080933. The reversal of 21080931 is 13908012.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a de Polignac number, because none of the positive numbers 2^k-21080931 is a prime.

It is a super-2 number, since 2×21080931² = 888811303653522, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (21080933) 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, 4225 + ... + 7746.

It is an arithmetic number, because the mean of its divisors is an integer number (3519768).

Almost surely, 2^21080931 is an apocalyptic number.

21080931 is a deficient number, since it is larger than the sum of its proper divisors (7077213).

21080931 is a wasteful number, since it uses less digits than its factorization.

21080931 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 12561.

The product of its (nonzero) digits is 432, while the sum is 24.

The square root of 21080931 is about 4591.3974996726. The cubic root of 21080931 is about 276.2463799748.

Adding to 21080931 its reverse (13908012), we get a palindrome (34988943).

The spelling of 21080931 in words is "twenty-one million, eighty thousand, nine hundred thirty-one".