21333131 has 4 divisors (see below), whose sum is σ = 21371064. Its totient is φ = 21295200.

The previous prime is 21333107. The next prime is 21333133. The reversal of 21333131 is 13133312.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 21333131 - 2²² = 17138827 is a prime.

It is a super-2 number, since 2×21333131² = 910204956526322, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21333133) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 18110 + ... + 19251.

It is an arithmetic number, because the mean of its divisors is an integer number (5342766).

Almost surely, 2^21333131 is an apocalyptic number.

21333131 is a deficient number, since it is larger than the sum of its proper divisors (37933).

21333131 is an equidigital number, since it uses as much as digits as its factorization.

21333131 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 37932.

The product of its digits is 162, while the sum is 17.

The square root of 21333131 is about 4618.7802502392. The cubic root of 21333131 is about 277.3436329244.

Adding to 21333131 its reverse (13133312), we get a palindrome (34466443).

The spelling of 21333131 in words is "twenty-one million, three hundred thirty-three thousand, one hundred thirty-one".