131115721 has 6 divisors (see below), whose sum is σ = 144119066. Its totient is φ = 119196000.

The previous prime is 131115707. The next prime is 131115731. The reversal of 131115721 is 127511131.

It can be written as a sum of positive squares in only one way, i.e., 116208400 + 14907321 = 10780^2 + 3861^2 .

It is not a de Polignac number, because 131115721 - 2¹⁷ = 130984649 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 131115692 and 131115701.

It is not an unprimeable number, because it can be changed into a prime (131115731) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 541680 + ... + 541921.

Almost surely, 2^131115721 is an apocalyptic number.

131115721 is a gapful number since it is divisible by the number (11) formed by its first and last digit.

It is an amenable number.

131115721 is a deficient number, since it is larger than the sum of its proper divisors (13003345).

131115721 is a wasteful number, since it uses less digits than its factorization.

131115721 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1083623 (or 1083612 counting only the distinct ones).

The product of its digits is 210, while the sum is 22.

The square root of 131115721 is about 11450.5773216899. The cubic root of 131115721 is about 508.0248104629.

Adding to 131115721 its reverse (127511131), we get a palindrome (258626852).

The spelling of 131115721 in words is "one hundred thirty-one million, one hundred fifteen thousand, seven hundred twenty-one".