621166235881 has 9 divisors (see below), whose sum is σ = 649366641021. Its totient is φ = 594141669132.

The previous prime is 621166235861. The next prime is 621166235909. The reversal of 621166235881 is 188532661126.

The square root of 621166235881 is 788141.

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

It is not a de Polignac number, because 621166235881 - 2⁵ = 621166235849 is a prime.

It is a super-2 number, since 2×621166235881² (a number of 24 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (621166235861) 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, 18110110 + ... + 18144376.

Almost surely, 2^621166235881 is an apocalyptic number.

621166235881 is the 788141-st square number.

621166235881 is the 394071-st centered octagonal number.

It is an amenable number.

621166235881 is a deficient number, since it is larger than the sum of its proper divisors (28200405140).

621166235881 is an frugal number, since it uses more digits than its factorization.

621166235881 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 68580 (or 34290 counting only the distinct ones).

The product of its digits is 829440, while the sum is 49.

Multiplying 621166235881 by its sum of digits (49), we get a square (30437145558169 = 5516987²).

The spelling of 621166235881 in words is "six hundred twenty-one billion, one hundred sixty-six million, two hundred thirty-five thousand, eight hundred eighty-one".