16311121225 has 81 divisors (see below), whose sum is σ = 24389817951. Its totient is φ = 10789363200.

The previous prime is 16311121219. The next prime is 16311121261. The reversal of 16311121225 is 52212111361.

The square root of 16311121225 is 127715.

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

It can be written as a sum of positive squares in 13 ways, for example, as 15294021561 + 1017099664 = 123669^2 + 31892^2 .

It is not a de Polignac number, because 16311121225 - 2²³ = 16302732617 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (25).

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 16311121225.

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, 183270981 + ... + 183271069.

Almost surely, 2^16311121225 is an apocalyptic number.

16311121225 is the 127715-th square number.

16311121225 is the 63858-th centered octagonal number.

It is an amenable number.

16311121225 is a deficient number, since it is larger than the sum of its proper divisors (8078696726).

16311121225 is an frugal number, since it uses more digits than its factorization.

16311121225 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 284 (or 142 counting only the distinct ones).

The product of its digits is 720, while the sum is 25.

Multiplying 16311121225 by its sum of digits (25), we get a square (407778030625 = 638575²).

16311121225 divided by its sum of digits (25) gives a square (652444849 = 25543²).

Adding to 16311121225 its reverse (52212111361), we get a palindrome (68523232586).

The spelling of 16311121225 in words is "sixteen billion, three hundred eleven million, one hundred twenty-one thousand, two hundred twenty-five".