1621323857664 has 432 divisors, whose sum is σ = 5391218589120. Its totient is φ = 459027578880.

The previous prime is 1621323857639. The next prime is 1621323857687. The reversal of 1621323857664 is 4667583231261.

1621323857664 is a `hidden beast` number, since 1 + 6 + 2 + 1 + 3 + 2 + 3 + 8 + 576 + 64 = 666.

It is a self number, because there is not a number n which added to its sum of digits gives 1621323857664.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 1319221402 + ... + 1319222630.

It is an arithmetic number, because the mean of its divisors is an integer number (12479672660).

Almost surely, 2^{1621323857664} is an apocalyptic number.

1621323857664 is a gapful number since it is divisible by the number (14) 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 1621323857664, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (2695609294560).

1621323857664 is an abundant number, since it is smaller than the sum of its proper divisors (3769894731456).

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

1621323857664 is a wasteful number, since it uses less digits than its factorization.

1621323857664 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1936 (or 1919 counting only the distinct ones).

The product of its digits is 8709120, while the sum is 54.

The spelling of 1621323857664 in words is "one trillion, six hundred twenty-one billion, three hundred twenty-three million, eight hundred fifty-seven thousand, six hundred sixty-four".