64398817665 has 640 divisors, whose sum is σ = 162628300800. Its totient is φ = 23897825280.

The previous prime is 64398817657. The next prime is 64398817667. The reversal of 64398817665 is 56671889346.

It is not a de Polignac number, because 64398817665 - 2³ = 64398817657 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (63).

Its product of digits (52254720) is a multiple of the sum of its prime divisors (105).

It is not an unprimeable number, because it can be changed into a prime (64398817667) by changing a digit.

It is a polite number, since it can be written in 639 ways as a sum of consecutive naturals, for example, 2077381200 + ... + 2077381230.

It is an arithmetic number, because the mean of its divisors is an integer number (254106720).

Almost surely, 2^64398817665 is an apocalyptic number.

64398817665 is a gapful number since it is divisible by the number (65) formed by its first and last digit.

It is an amenable number.

64398817665 is an abundant number, since it is smaller than the sum of its proper divisors (98229483135).

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

64398817665 is a wasteful number, since it uses less digits than its factorization.

64398817665 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 132 (or 105 counting only the distinct ones).

The product of its digits is 52254720, while the sum is 63.

The spelling of 64398817665 in words is "sixty-four billion, three hundred ninety-eight million, eight hundred seventeen thousand, six hundred sixty-five".