131356721 has 4 divisors (see below), whose sum is σ = 132711012. Its totient is φ = 130002432.

The previous prime is 131356639. The next prime is 131356727. The reversal of 131356721 is 127653131.

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

It can be written as a sum of positive squares in 2 ways, for example, as 74580496 + 56776225 = 8636^2 + 7535^2 .

It is a cyclic number.

It is not a de Polignac number, because 131356721 - 2²² = 127162417 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (131356727) 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, 677000 + ... + 677193.

It is an arithmetic number, because the mean of its divisors is an integer number (33177753).

Almost surely, 2^131356721 is an apocalyptic number.

It is an amenable number.

131356721 is a deficient number, since it is larger than the sum of its proper divisors (1354291).

131356721 is an equidigital number, since it uses as much as digits as its factorization.

131356721 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1354290.

The product of its digits is 3780, while the sum is 29.

The square root of 131356721 is about 11461.0959772615. The cubic root of 131356721 is about 508.3358818350.

The spelling of 131356721 in words is "one hundred thirty-one million, three hundred fifty-six thousand, seven hundred twenty-one".