664051661 has 8 divisors (see below), whose sum is σ = 817294464. Its totient is φ = 525403440.

The previous prime is 664051639. The next prime is 664051679. The reversal of 664051661 is 166150466.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-664051661 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (664051361) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 3648545 + ... + 3648726.

It is an arithmetic number, because the mean of its divisors is an integer number (102161808).

Almost surely, 2^664051661 is an apocalyptic number.

It is an amenable number.

664051661 is a deficient number, since it is larger than the sum of its proper divisors (153242803).

664051661 is a wasteful number, since it uses less digits than its factorization.

664051661 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7297291.

The product of its (nonzero) digits is 25920, while the sum is 35.

The square root of 664051661 is about 25769.1998517610. The cubic root of 664051661 is about 872.4367590991.

The spelling of 664051661 in words is "six hundred sixty-four million, fifty-one thousand, six hundred sixty-one".