16221843225 has 81 divisors (see below), whose sum is σ = 33826704093. Its totient is φ = 7409586240.

The previous prime is 16221843203. The next prime is 16221843257. The reversal of 16221843225 is 52234812261.

The square root of 16221843225 is 127365.

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

16221843225 is a `hidden beast` number, since 1 + 6 + 2 + 218 + 432 + 2 + 5 = 666.

It can be written as a sum of positive squares in 4 ways, for example, as 7116103449 + 9105739776 = 84357^2 + 95424^2 .

It is not a de Polignac number, because 16221843225 - 2¹⁹ = 16221318937 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 16221843225.

It is an unprimeable number.

It is a polite number, since it can be written in 80 ways as a sum of consecutive naturals, for example, 13372719 + ... + 13373931.

Almost surely, 2^16221843225 is an apocalyptic number.

16221843225 is a gapful number since it is divisible by the number (15) formed by its first and last digit.

16221843225 is the 127365-th square number.

16221843225 is the 63683-rd centered octagonal number.

It is an amenable number.

16221843225 is an abundant number, since it is smaller than the sum of its proper divisors (17604860868).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

16221843225 is an equidigital number, since it uses as much as digits as its factorization.

16221843225 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2456 (or 1228 counting only the distinct ones).

The product of its digits is 46080, while the sum is 36.

Multiplying 16221843225 by its sum of digits (36), we get a square (583986356100 = 764190²).

The spelling of 16221843225 in words is "sixteen billion, two hundred twenty-one million, eight hundred forty-three thousand, two hundred twenty-five".