131981221 has 2 divisors, whose sum is σ = 131981222. Its totient is φ = 131981220.

The previous prime is 131981203. The next prime is 131981243. The reversal of 131981221 is 122189131.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 104837121 + 27144100 = 10239^2 + 5210^2 .

It is an emirp because it is prime and its reverse (122189131) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 131981221 - 2⁵ = 131981189 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 131981221.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (131981021) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 65990610 + 65990611.

It is an arithmetic number, because the mean of its divisors is an integer number (65990611).

Almost surely, 2^131981221 is an apocalyptic number.

It is an amenable number.

131981221 is a deficient number, since it is larger than the sum of its proper divisors (1).

131981221 is an equidigital number, since it uses as much as digits as its factorization.

131981221 is an evil number, because the sum of its binary digits is even.

The product of its digits is 864, while the sum is 28.

The square root of 131981221 is about 11488.3080129321. The cubic root of 131981221 is about 509.1401903737.

The spelling of 131981221 in words is "one hundred thirty-one million, nine hundred eighty-one thousand, two hundred twenty-one".