135661396531 has 4 divisors (see below), whose sum is σ = 137295871272. Its totient is φ = 134026921792.

The previous prime is 135661396517. The next prime is 135661396537. The reversal of 135661396531 is 135693166531.

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

It is a cyclic number.

It is not a de Polignac number, because 135661396531 - 2²⁵ = 135627842099 is a prime.

It is a super-2 number, since 2×135661396531² (a number of 23 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (135661396537) 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, 817237246 + ... + 817237411.

It is an arithmetic number, because the mean of its divisors is an integer number (34323967818).

Almost surely, 2^135661396531 is an apocalyptic number.

135661396531 is a deficient number, since it is larger than the sum of its proper divisors (1634474741).

135661396531 is an equidigital number, since it uses as much as digits as its factorization.

135661396531 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1634474740.

The product of its digits is 1312200, while the sum is 49.

The spelling of 135661396531 in words is "one hundred thirty-five billion, six hundred sixty-one million, three hundred ninety-six thousand, five hundred thirty-one".