131125721 has 4 divisors (see below), whose sum is σ = 131176500. Its totient is φ = 131074944.

The previous prime is 131125717. The next prime is 131125727. The reversal of 131125721 is 127521131.

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 71233600 + 59892121 = 8440^2 + 7739^2 .

It is a cyclic number.

It is not a de Polignac number, because 131125721 - 2² = 131125717 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (131125727) 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, 21296 + ... + 26753.

It is an arithmetic number, because the mean of its divisors is an integer number (32794125).

Almost surely, 2^131125721 is an apocalyptic number.

It is an amenable number.

131125721 is a deficient number, since it is larger than the sum of its proper divisors (50779).

131125721 is an equidigital number, since it uses as much as digits as its factorization.

131125721 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 50778.

The product of its digits is 420, while the sum is 23.

The square root of 131125721 is about 11451.0139725703. The cubic root of 131125721 is about 508.0377255654.

Adding to 131125721 its reverse (127521131), we get a palindrome (258646852).

The spelling of 131125721 in words is "one hundred thirty-one million, one hundred twenty-five thousand, seven hundred twenty-one".