664843615657 has 16 divisors (see below), whose sum is σ = 771215735808. Its totient is φ = 568083003840.

The previous prime is 664843615649. The next prime is 664843615673. The reversal of 664843615657 is 756516348466.

It is a cyclic number.

It is not a de Polignac number, because 664843615657 - 2³ = 664843615649 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 664843615595 and 664843615604.

It is not an unprimeable number, because it can be changed into a prime (664843615637) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 35854558 + ... + 35873095.

It is an arithmetic number, because the mean of its divisors is an integer number (48200983488).

Almost surely, 2^664843615657 is an apocalyptic number.

It is an amenable number.

664843615657 is a deficient number, since it is larger than the sum of its proper divisors (106372120151).

664843615657 is a wasteful number, since it uses less digits than its factorization.

664843615657 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 71727720.

The product of its digits is 87091200, while the sum is 61.

The spelling of 664843615657 in words is "six hundred sixty-four billion, eight hundred forty-three million, six hundred fifteen thousand, six hundred fifty-seven".