664565651 has 4 divisors (see below), whose sum is σ = 664617432. Its totient is φ = 664513872.

The previous prime is 664565599. The next prime is 664565677. The reversal of 664565651 is 156565466.

It is a happy number.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It is a cyclic number.

It is not a de Polignac number, because 664565651 - 2¹⁰ = 664564627 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (664565851) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 9356 + ... + 37638.

It is an arithmetic number, because the mean of its divisors is an integer number (166154358).

Almost surely, 2^664565651 is an apocalyptic number.

664565651 is a deficient number, since it is larger than the sum of its proper divisors (51781).

664565651 is a wasteful number, since it uses less digits than its factorization.

664565651 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 51780.

The product of its digits is 648000, while the sum is 44.

The square root of 664565651 is about 25779.1708749525. The cubic root of 664565651 is about 872.6617958693.

The spelling of 664565651 in words is "six hundred sixty-four million, five hundred sixty-five thousand, six hundred fifty-one".