664977 has 4 divisors (see below), whose sum is σ = 886640. Its totient is φ = 443316.

The previous prime is 664973. The next prime is 664997. The reversal of 664977 is 779466.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is not a de Polignac number, because 664977 - 2² = 664973 is a prime.

It is a D-number.

It is a Duffinian number.

664977 is a lucky number.

It is not an unprimeable number, because it can be changed into a prime (664973) 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, 110827 + ... + 110832.

It is an arithmetic number, because the mean of its divisors is an integer number (221660).

2⁶⁶⁴⁹⁷⁷ is an apocalyptic number.

It is an amenable number.

664977 is a deficient number, since it is larger than the sum of its proper divisors (221663).

664977 is a wasteful number, since it uses less digits than its factorization.

664977 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 221662.

The product of its digits is 63504, while the sum is 39.

The square root of 664977 is about 815.4612191883. The cubic root of 664977 is about 87.2841810449.

The spelling of 664977 in words is "six hundred sixty-four thousand, nine hundred seventy-seven".