664328515491 has 40 divisors (see below), whose sum is σ = 1021707234240. Its totient is φ = 429861416832.

The previous prime is 664328515489. The next prime is 664328515517. The reversal of 664328515491 is 194515823466.

664328515491 is a `hidden beast` number, since 6 + 6 + 4 + 32 + 8 + 515 + 4 + 91 = 666.

664328515491 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is not a de Polignac number, because 664328515491 - 2¹ = 664328515489 is a prime.

It is not an unprimeable number, because it can be changed into a prime (664328515421) by changing a digit.

It is a polite number, since it can be written in 39 ways as a sum of consecutive naturals, for example, 954790 + ... + 1496756.

It is an arithmetic number, because the mean of its divisors is an integer number (25542680856).

Almost surely, 2^664328515491 is an apocalyptic number.

664328515491 is a deficient number, since it is larger than the sum of its proper divisors (357378718749).

664328515491 is a wasteful number, since it uses less digits than its factorization.

664328515491 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 542425 (or 542416 counting only the distinct ones).

The product of its digits is 6220800, while the sum is 54.

The spelling of 664328515491 in words is "six hundred sixty-four billion, three hundred twenty-eight million, five hundred fifteen thousand, four hundred ninety-one".