664889620677840 has 480 divisors, whose sum is σ = 2385071790206976. Its totient is φ = 165408391249920.

The previous prime is 664889620677787. The next prime is 664889620677869. The reversal of 664889620677840 is 48776026988466.

664889620677840 is a `hidden beast` number, since 6 + 6 + 488 + 9 + 6 + 2 + 0 + 67 + 78 + 4 + 0 = 666.

It is a self number, because there is not a number n which added to its sum of digits gives 664889620677840.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 95 ways as a sum of consecutive naturals, for example, 1698850975 + ... + 1699242305.

Almost surely, 2^{664889620677840} is an apocalyptic number.

664889620677840 is a gapful number since it is divisible by the number (60) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 664889620677840, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1192535895103488).

664889620677840 is an abundant number, since it is smaller than the sum of its proper divisors (1720182169529136).

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

664889620677840 is a wasteful number, since it uses less digits than its factorization.

664889620677840 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 392587 (or 392578 counting only the distinct ones).

The product of its (nonzero) digits is 9364045824, while the sum is 81.

The spelling of 664889620677840 in words is "six hundred sixty-four trillion, eight hundred eighty-nine billion, six hundred twenty million, six hundred seventy-seven thousand, eight hundred forty".