65631312509 has 18 divisors (see below), whose sum is σ = 78465899610. Its totient is φ = 54734938272.

The previous prime is 65631312469. The next prime is 65631312511. The reversal of 65631312509 is 90521313656.

It can be written as a sum of positive squares in 3 ways, for example, as 53636244025 + 11995068484 = 231595^2 + 109522^2 .

It is not a de Polignac number, because 65631312509 - 2²⁴ = 65614535293 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (65631312529) by changing a digit.

It is a polite number, since it can be written in 17 ways as a sum of consecutive naturals, for example, 422114 + ... + 556275.

It is an arithmetic number, because the mean of its divisors is an integer number (4359216645).

Almost surely, 2^65631312509 is an apocalyptic number.

It is an amenable number.

65631312509 is a deficient number, since it is larger than the sum of its proper divisors (12834587101).

65631312509 is an equidigital number, since it uses as much as digits as its factorization.

65631312509 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 978477 (or 978433 counting only the distinct ones).

The product of its (nonzero) digits is 145800, while the sum is 41.

The spelling of 65631312509 in words is "sixty-five billion, six hundred thirty-one million, three hundred twelve thousand, five hundred nine".