621328358278681 has 9 divisors (see below), whose sum is σ = 621661429534719. Its totient is φ = 620995465418736.

The previous prime is 621328358278609. The next prime is 621328358278697. The reversal of 621328358278681 is 186872853823126.

The square root of 621328358278681 is 24926459.

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

It can be written as a sum of positive squares in only one way, i.e., 2792357971225 + 618536000307456 = 1671035^2 + 24870384^2 .

It is not a de Polignac number, because 621328358278681 - 2⁹ = 621328358278169 is a prime.

It is a super-2 number, since 2×621328358278681² (a number of 30 digits) contains 22 as substring.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 621328358278681.

It is not an unprimeable number, because it can be changed into a prime (621328358278081) 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, 55910041981 + ... + 55910053093.

Almost surely, 2^{621328358278681} is an apocalyptic number.

621328358278681 is the 24926459-th square number.

621328358278681 is the 12463230-th centered octagonal number.

It is an amenable number.

621328358278681 is a deficient number, since it is larger than the sum of its proper divisors (333071256038).

621328358278681 is an frugal number, since it uses more digits than its factorization.

621328358278681 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 26712 (or 13356 counting only the distinct ones).

The product of its digits is 371589120, while the sum is 70.

The spelling of 621328358278681 in words is "six hundred twenty-one trillion, three hundred twenty-eight billion, three hundred fifty-eight million, two hundred seventy-eight thousand, six hundred eighty-one".