1621587736720 has 640 divisors, whose sum is σ = 4735168358400. Its totient is φ = 515022520320.

The previous prime is 1621587736667. The next prime is 1621587736721. The reversal of 1621587736720 is 276377851261.

It is a hoax number, since the sum of its digits (55) coincides with the sum of the digits of its distinct prime factors.

It is not an unprimeable number, because it can be changed into a prime (1621587736721) by changing a digit.

It is a polite number, since it can be written in 127 ways as a sum of consecutive naturals, for example, 2810377072 + ... + 2810377648.

It is an arithmetic number, because the mean of its divisors is an integer number (7398700560).

Almost surely, 2^{1621587736720} is an apocalyptic number.

1621587736720 is a gapful number since it is divisible by the number (10) 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 1621587736720, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (2367584179200).

1621587736720 is an abundant number, since it is smaller than the sum of its proper divisors (3113580621680).

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

1621587736720 is a wasteful number, since it uses less digits than its factorization.

1621587736720 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 768 (or 748 counting only the distinct ones).

The product of its (nonzero) digits is 5927040, while the sum is 55.

The spelling of 1621587736720 in words is "one trillion, six hundred twenty-one billion, five hundred eighty-seven million, seven hundred thirty-six thousand, seven hundred twenty".