664198561 has 24 divisors (see below), whose sum is σ = 769712640. Its totient is φ = 571147200.

The previous prime is 664198559. The next prime is 664198567. The reversal of 664198561 is 165891466.

It is not a de Polignac number, because 664198561 - 2¹ = 664198559 is a prime.

It is not an unprimeable number, because it can be changed into a prime (664198567) 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 23 ways as a sum of consecutive naturals, for example, 194176 + ... + 197566.

It is an arithmetic number, because the mean of its divisors is an integer number (32071360).

Almost surely, 2^664198561 is an apocalyptic number.

664198561 is a gapful number since it is divisible by the number (61) formed by its first and last digit.

664198561 is the 14880-th hex number.

It is an amenable number.

664198561 is a deficient number, since it is larger than the sum of its proper divisors (105514079).

664198561 is a wasteful number, since it uses less digits than its factorization.

664198561 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3497 (or 3484 counting only the distinct ones).

The product of its digits is 311040, while the sum is 46.

The square root of 664198561 is about 25772.0499960713. The cubic root of 664198561 is about 872.5010871818.

The spelling of 664198561 in words is "six hundred sixty-four million, one hundred ninety-eight thousand, five hundred sixty-one".