621721211049 has 27 divisors (see below), whose sum is σ = 901605881943. Its totient is φ = 412842318912.

The previous prime is 621721211029. The next prime is 621721211051. The reversal of 621721211049 is 940112127126.

The square root of 621721211049 is 788493.

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

621721211049 is a `hidden beast` number, since 621 + 7 + 2 + 1 + 21 + 1 + 0 + 4 + 9 = 666.

It can be written as a sum of positive squares in only one way, i.e., 69719762025 + 552001449024 = 264045^2 + 742968^2 .

It is a de Polignac number, because none of the positive numbers 2^k-621721211049 is a prime.

It is not an unprimeable number, because it can be changed into a prime (621721211029) by changing a digit.

It is a polite number, since it can be written in 26 ways as a sum of consecutive naturals, for example, 1024252104 + ... + 1024252710.

Almost surely, 2^621721211049 is an apocalyptic number.

621721211049 is the 788493-rd square number.

621721211049 is the 394247-th centered octagonal number.

It is an amenable number.

621721211049 is a deficient number, since it is larger than the sum of its proper divisors (279884670894).

621721211049 is an frugal number, since it uses more digits than its factorization.

621721211049 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2086 (or 1043 counting only the distinct ones).

The product of its (nonzero) digits is 12096, while the sum is 36.

Multiplying 621721211049 by its sum of digits (36), we get a square (22381963597764 = 4730958²).

The spelling of 621721211049 in words is "six hundred twenty-one billion, seven hundred twenty-one million, two hundred eleven thousand, forty-nine".