664721654 has 16 divisors (see below), whose sum is σ = 1048671360. Its totient is φ = 315569280.

The previous prime is 664721639. The next prime is 664721677. The reversal of 664721654 is 456127466.

It is a happy number.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 97859 + ... + 104430.

It is an arithmetic number, because the mean of its divisors is an integer number (65541960).

Almost surely, 2^664721654 is an apocalyptic number.

664721654 is a deficient number, since it is larger than the sum of its proper divisors (383949706).

664721654 is a wasteful number, since it uses less digits than its factorization.

664721654 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 202375.

The product of its digits is 241920, while the sum is 41.

The square root of 664721654 is about 25782.1964541425. The cubic root of 664721654 is about 872.7300746550.

The spelling of 664721654 in words is "six hundred sixty-four million, seven hundred twenty-one thousand, six hundred fifty-four".