664376421 has 4 divisors (see below), whose sum is σ = 885835232. Its totient is φ = 442917612.

The previous prime is 664376417. The next prime is 664376441. The reversal of 664376421 is 124673466.

It is a happy number.

664376421 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

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 664376421 - 2² = 664376417 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 664376421.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (664376411) 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, 110729401 + ... + 110729406.

It is an arithmetic number, because the mean of its divisors is an integer number (221458808).

Almost surely, 2^664376421 is an apocalyptic number.

It is an amenable number.

664376421 is a deficient number, since it is larger than the sum of its proper divisors (221458811).

664376421 is a wasteful number, since it uses less digits than its factorization.

664376421 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 221458810.

The product of its digits is 145152, while the sum is 39.

The square root of 664376421 is about 25775.5004025140. The cubic root of 664376421 is about 872.5789600765.

The spelling of 664376421 in words is "six hundred sixty-four million, three hundred seventy-six thousand, four hundred twenty-one".