664191864 has 144 divisors (see below), whose sum is σ = 2160400320. Its totient is φ = 183617280.

The previous prime is 664191863. The next prime is 664191893. The reversal of 664191864 is 468191466.

It is a nude number because it is divisible by every one of its digits.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (664191863) by changing a digit.

It is a polite number, since it can be written in 35 ways as a sum of consecutive naturals, for example, 106332 + ... + 112404.

It is an arithmetic number, because the mean of its divisors is an integer number (15002780).

Almost surely, 2^664191864 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 664191864, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1080200160).

664191864 is an abundant number, since it is smaller than the sum of its proper divisors (1496208456).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

664191864 is a wasteful number, since it uses less digits than its factorization.

664191864 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6130 (or 6116 counting only the distinct ones).

The product of its digits is 248832, while the sum is 45.

The square root of 664191864 is about 25771.9200681672. The cubic root of 664191864 is about 872.4981547458.

The spelling of 664191864 in words is "six hundred sixty-four million, one hundred ninety-one thousand, eight hundred sixty-four".