221312131 has 4 divisors (see below), whose sum is σ = 228451264. Its totient is φ = 214173000.

The previous prime is 221312081. The next prime is 221312149. The reversal of 221312131 is 131213122.

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 221312131 - 2⁹ = 221311619 is a prime.

It is a super-2 number, since 2×221312131² = 97958118655522322, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (221312191) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 3569520 + ... + 3569581.

It is an arithmetic number, because the mean of its divisors is an integer number (57112816).

Almost surely, 2^221312131 is an apocalyptic number.

221312131 is a deficient number, since it is larger than the sum of its proper divisors (7139133).

221312131 is an equidigital number, since it uses as much as digits as its factorization.

221312131 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7139132.

The product of its digits is 72, while the sum is 16.

The square root of 221312131 is about 14876.5631447589. The cubic root of 221312131 is about 604.8788601570.

Adding to 221312131 its reverse (131213122), we get a palindrome (352525253).

Subtracting from 221312131 its reverse (131213122), we obtain a palindrome (90099009).

It can be divided in two parts, 22 and 1312131, that multiplied together give a palindrome (28866882).

The spelling of 221312131 in words is "two hundred twenty-one million, three hundred twelve thousand, one hundred thirty-one".