664923987 has 48 divisors (see below), whose sum is σ = 1185184000. Its totient is φ = 349811136.

The previous prime is 664923967. The next prime is 664924031. The reversal of 664923987 is 789329466.

It is a happy number.

664923987 is a `hidden beast` number, since 66 + 492 + 3 + 98 + 7 = 666.

It is not a de Polignac number, because 664923987 - 2¹⁶ = 664858451 is a prime.

It is not an unprimeable number, because it can be changed into a prime (664923967) by changing a digit.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 407868 + ... + 409494.

Almost surely, 2^664923987 is an apocalyptic number.

664923987 is a deficient number, since it is larger than the sum of its proper divisors (520260013).

664923987 is a wasteful number, since it uses less digits than its factorization.

664923987 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2152 (or 2149 counting only the distinct ones).

The product of its digits is 3919104, while the sum is 54.

The square root of 664923987 is about 25786.1200454818. The cubic root of 664923987 is about 872.8186150637.

The spelling of 664923987 in words is "six hundred sixty-four million, nine hundred twenty-three thousand, nine hundred eighty-seven".