131640661 has 4 divisors (see below), whose sum is σ = 137364192. Its totient is φ = 125917132.

The previous prime is 131640643. The next prime is 131640667. The reversal of 131640661 is 166046131.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 131640661 - 2⁵ = 131640629 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (131640667) 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, 2861731 + ... + 2861776.

It is an arithmetic number, because the mean of its divisors is an integer number (34341048).

Almost surely, 2^131640661 is an apocalyptic number.

It is an amenable number.

131640661 is a deficient number, since it is larger than the sum of its proper divisors (5723531).

131640661 is an equidigital number, since it uses as much as digits as its factorization.

131640661 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5723530.

The product of its (nonzero) digits is 2592, while the sum is 28.

The square root of 131640661 is about 11473.4764130145. The cubic root of 131640661 is about 508.7018903006.

Adding to 131640661 its reverse (166046131), we get a palindrome (297686792).

The spelling of 131640661 in words is "one hundred thirty-one million, six hundred forty thousand, six hundred sixty-one".