21331131 has 16 divisors (see below), whose sum is σ = 29488128. Its totient is φ = 13701600.

The previous prime is 21331127. The next prime is 21331133. The reversal of 21331131 is 13113312.

It is not a de Polignac number, because 21331131 - 2² = 21331127 is a prime.

It is a super-2 number, since 2×21331131² = 910034299478322, which contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 21331131.

It is not an unprimeable number, because it can be changed into a prime (21331133) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 31941 + ... + 32601.

It is an arithmetic number, because the mean of its divisors is an integer number (1843008).

Almost surely, 2^21331131 is an apocalyptic number.

21331131 is a deficient number, since it is larger than the sum of its proper divisors (8156997).

21331131 is a wasteful number, since it uses less digits than its factorization.

21331131 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1042.

The product of its digits is 54, while the sum is 15.

The square root of 21331131 is about 4618.5637377869. The cubic root of 21331131 is about 277.3349655828.

Adding to 21331131 its reverse (13113312), we get a palindrome (34444443).

The spelling of 21331131 in words is "twenty-one million, three hundred thirty-one thousand, one hundred thirty-one".