621186978761 has 18 divisors (see below), whose sum is σ = 644531585418. Its totient is φ = 598330705440.

The previous prime is 621186978719. The next prime is 621186978773. The reversal of 621186978761 is 167879681126.

It can be written as a sum of positive squares in only one way, i.e., 378772548025 + 242414430736 = 615445^2 + 492356^2 .

It is not a de Polignac number, because 621186978761 - 2²² = 621182784457 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 621186978694 and 621186978703.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (621186978791) by changing a digit.

It is a polite number, since it can be written in 17 ways as a sum of consecutive naturals, for example, 418871126 + ... + 418872608.

It is an arithmetic number, because the mean of its divisors is an integer number (35807310301).

Almost surely, 2^621186978761 is an apocalyptic number.

It is an amenable number.

621186978761 is a deficient number, since it is larger than the sum of its proper divisors (23344606657).

621186978761 is an frugal number, since it uses more digits than its factorization.

621186978761 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3173 (or 1607 counting only the distinct ones).

The product of its digits is 12192768, while the sum is 62.

The spelling of 621186978761 in words is "six hundred twenty-one billion, one hundred eighty-six million, nine hundred seventy-eight thousand, seven hundred sixty-one".