1620888005881 has 9 divisors (see below), whose sum is σ = 1632981386701. Its totient is φ = 1608883559392.

The previous prime is 1620888005873. The next prime is 1620888005909. The reversal of 1620888005881 is 1885008880261.

The square root of 1620888005881 is 1273141.

It is a perfect power (a square), and thus also a powerful number.

It can be written as a sum of positive squares in 4 ways, for example, as 266969589481 + 1353918416400 = 516691^2 + 1163580^2 .

It is not a de Polignac number, because 1620888005881 - 2³ = 1620888005873 is a prime.

It is a super-2 number, since 2×1620888005881² (a number of 25 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1620888005861) by changing a digit.

It is a polite number, since it can be written in 8 ways as a sum of consecutive naturals, for example, 174415671 + ... + 174424963.

Almost surely, 2^{1620888005881} is an apocalyptic number.

1620888005881 is the 1273141-st square number.

1620888005881 is the 636571-st centered octagonal number.

It is an amenable number.

1620888005881 is a deficient number, since it is larger than the sum of its proper divisors (12093380820).

1620888005881 is an frugal number, since it uses more digits than its factorization.

1620888005881 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 18860 (or 9430 counting only the distinct ones).

The product of its (nonzero) digits is 1966080, while the sum is 55.

The spelling of 1620888005881 in words is "one trillion, six hundred twenty billion, eight hundred eighty-eight million, five thousand, eight hundred eighty-one".