664297840 has 20 divisors (see below), whose sum is σ = 1544492664. Its totient is φ = 265719104.

The previous prime is 664297789. The next prime is 664297849. The reversal of 664297840 is 48792466.

It is a happy number.

It is a tau number, because it is divible by the number of its divisors (20).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (664297849) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 4151782 + ... + 4151941.

Almost surely, 2^664297840 is an apocalyptic number.

It is an amenable number.

664297840 is an abundant number, since it is smaller than the sum of its proper divisors (880194824).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

664297840 is a wasteful number, since it uses less digits than its factorization.

664297840 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 8303736 (or 8303730 counting only the distinct ones).

The product of its (nonzero) digits is 580608, while the sum is 46.

The square root of 664297840 is about 25773.9760223369. The cubic root of 664297840 is about 872.5445564720.

The spelling of 664297840 in words is "six hundred sixty-four million, two hundred ninety-seven thousand, eight hundred forty".