21239131 has 8 divisors (see below), whose sum is σ = 22664720. Its totient is φ = 19844352.

The previous prime is 21239087. The next prime is 21239173. The reversal of 21239131 is 13193212.

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

It is a cyclic number.

It is not a de Polignac number, because 21239131 - 2⁹ = 21238619 is a prime.

It is a super-2 number, since 2×21239131² = 902201371270322, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (21239191) by changing a digit.

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, 6270 + ... + 9043.

It is an arithmetic number, because the mean of its divisors is an integer number (2833090).

Almost surely, 2^21239131 is an apocalyptic number.

21239131 is a deficient number, since it is larger than the sum of its proper divisors (1425589).

21239131 is a wasteful number, since it uses less digits than its factorization.

21239131 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 15405.

The product of its digits is 324, while the sum is 22.

The square root of 21239131 is about 4608.5931692871. The cubic root of 21239131 is about 276.9356808267.

The spelling of 21239131 in words is "twenty-one million, two hundred thirty-nine thousand, one hundred thirty-one".