664967021 has 8 divisors (see below), whose sum is σ = 668441088. Its totient is φ = 661500000.

The previous prime is 664967003. The next prime is 664967029. The reversal of 664967021 is 120769466.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 664967021 - 2¹⁰ = 664965997 is a prime.

It is a super-2 number, since 2×664967021² = 884362278035228882, which contains 22 as substring.

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 664967021.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (664967029) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 368321 + ... + 370121.

It is an arithmetic number, because the mean of its divisors is an integer number (83555136).

Almost surely, 2^664967021 is an apocalyptic number.

It is an amenable number.

664967021 is a deficient number, since it is larger than the sum of its proper divisors (3474067).

664967021 is a wasteful number, since it uses less digits than its factorization.

664967021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3523.

The product of its (nonzero) digits is 108864, while the sum is 41.

The square root of 664967021 is about 25786.9544731440. The cubic root of 664967021 is about 872.8374443167.

The spelling of 664967021 in words is "six hundred sixty-four million, nine hundred sixty-seven thousand, twenty-one".