664356424010661 has 18 divisors (see below), whose sum is σ = 1003162850713478. Its totient is φ = 423647574728400.

The previous prime is 664356424010651. The next prime is 664356424010761. The reversal of 664356424010661 is 166010424653466.

664356424010661 is a `hidden beast` number, since 6 + 6 + 4 + 3 + 56 + 424 + 0 + 106 + 61 = 666.

It can be written as a sum of positive squares in only one way, i.e., 409201517412900 + 255154906597761 = 20228730^2 + 15973569^2 .

It is not a de Polignac number, because 664356424010661 - 2¹⁰ = 664356424009637 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 664356424010598 and 664356424010607.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (664356424010651) 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, 69770676190 + ... + 69770685711.

Almost surely, 2^{664356424010661} is an apocalyptic number.

It is an amenable number.

664356424010661 is a deficient number, since it is larger than the sum of its proper divisors (338806426702817).

664356424010661 is a wasteful number, since it uses less digits than its factorization.

664356424010661 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 139541361953 (or 139541361927 counting only the distinct ones).

The product of its (nonzero) digits is 14929920, while the sum is 54.

The spelling of 664356424010661 in words is "six hundred sixty-four trillion, three hundred fifty-six billion, four hundred twenty-four million, ten thousand, six hundred sixty-one".