664465815 has 64 divisors (see below), whose sum is σ = 1339161600. Its totient is φ = 309889152.

The previous prime is 664465801. The next prime is 664465817. The reversal of 664465815 is 518564466.

664465815 is a `hidden beast` number, since 6 + 64 + 4 + 6 + 581 + 5 = 666.

It is not a de Polignac number, because 664465815 - 2⁸ = 664465559 is a prime.

It is a super-2 number, since 2×664465815² = 883029638607228450, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (45).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (664465817) by changing a digit.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 23382 + ... + 43308.

It is an arithmetic number, because the mean of its divisors is an integer number (20924400).

Almost surely, 2^664465815 is an apocalyptic number.

664465815 is a gapful number since it is divisible by the number (65) formed by its first and last digit.

664465815 is an abundant number, since it is smaller than the sum of its proper divisors (674695785).

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

664465815 is a wasteful number, since it uses less digits than its factorization.

664465815 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 19973 (or 19967 counting only the distinct ones).

The product of its digits is 691200, while the sum is 45.

The square root of 664465815 is about 25777.2344327315. The cubic root of 664465815 is about 872.6180944301.

The spelling of 664465815 in words is "six hundred sixty-four million, four hundred sixty-five thousand, eight hundred fifteen".