664027521891 has 8 divisors (see below), whose sum is σ = 885397781184. Its totient is φ = 442671138600.

The previous prime is 664027521889. The next prime is 664027521991. The reversal of 664027521891 is 198125720466.

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

It is not a de Polignac number, because 664027521891 - 2¹ = 664027521889 is a prime.

It is not an unprimeable number, because it can be changed into a prime (664027521821) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 3356821 + ... + 3549126.

It is an arithmetic number, because the mean of its divisors is an integer number (110674722648).

Almost surely, 2^664027521891 is an apocalyptic number.

664027521891 is a deficient number, since it is larger than the sum of its proper divisors (221370259293).

664027521891 is a wasteful number, since it uses less digits than its factorization.

664027521891 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6938001.

The product of its (nonzero) digits is 1451520, while the sum is 51.

The spelling of 664027521891 in words is "six hundred sixty-four billion, twenty-seven million, five hundred twenty-one thousand, eight hundred ninety-one".