661979530598400 has 3456 divisors, whose sum is σ = 2843580999168000. Its totient is φ = 144008832614400.

The previous prime is 661979530598381. The next prime is 661979530598467. The reversal of 661979530598400 is 4895035979166.

661979530598400 is a `hidden beast` number, since 6 + 6 + 1 + 9 + 7 + 9 + 530 + 5 + 9 + 84 + 0 + 0 = 666.

It is a Harshad number since it is a multiple of its sum of digits (72).

It is a congruent number.

It is an unprimeable number.

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 287 ways as a sum of consecutive naturals, for example, 2339150284659 + ... + 2339150284941.

It is an arithmetic number, because the mean of its divisors is an integer number (822795428000).

Almost surely, 2^{661979530598400} is an apocalyptic number.

661979530598400 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 661979530598400, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1421790499584000).

661979530598400 is an abundant number, since it is smaller than the sum of its proper divisors (2181601468569600).

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

661979530598400 is a wasteful number, since it uses less digits than its factorization.

661979530598400 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 665 (or 637 counting only the distinct ones).

The product of its (nonzero) digits is 440899200, while the sum is 72.

The spelling of 661979530598400 in words is "six hundred sixty-one trillion, nine hundred seventy-nine billion, five hundred thirty million, five hundred ninety-eight thousand, four hundred".