664051961 has 6 divisors (see below), whose sum is σ = 686164986. Its totient is φ = 642630000.

The previous prime is 664051937. The next prime is 664051979. The reversal of 664051961 is 169150466.

664051961 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It can be written as a sum of positive squares in only one way, i.e., 491287225 + 172764736 = 22165^2 + 13144^2 .

It is not a de Polignac number, because 664051961 - 2²² = 659857657 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (664051901) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 344540 + ... + 346461.

It is an arithmetic number, because the mean of its divisors is an integer number (114360831).

Almost surely, 2^664051961 is an apocalyptic number.

It is an amenable number.

664051961 is a deficient number, since it is larger than the sum of its proper divisors (22113025).

664051961 is an equidigital number, since it uses as much as digits as its factorization.

664051961 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 691063 (or 691032 counting only the distinct ones).

The product of its (nonzero) digits is 38880, while the sum is 38.

The square root of 664051961 is about 25769.2056726629. The cubic root of 664051961 is about 872.4368904799.

The spelling of 664051961 in words is "six hundred sixty-four million, fifty-one thousand, nine hundred sixty-one".