25851816225 has 81 divisors (see below), whose sum is σ = 48203353497. Its totient is φ = 13752905760.

The previous prime is 25851816203. The next prime is 25851816229. The reversal of 25851816225 is 52261815852.

The square root of 25851816225 is 160785.

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

25851816225 is a `hidden beast` number, since 2 + 5 + 8 + 5 + 18 + 1 + 622 + 5 = 666.

It can be written as a sum of positive squares in 4 ways, for example, as 26040609 + 25825775616 = 5103^2 + 160704^2 .

It is a tau number, because it is divible by the number of its divisors (81).

It is not a de Polignac number, because 25851816225 - 2⁷ = 25851816097 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (45).

It is not an unprimeable number, because it can be changed into a prime (25851816229) by changing a digit.

It is a polite number, since it can be written in 80 ways as a sum of consecutive naturals, for example, 65117727 + ... + 65118123.

Almost surely, 2^25851816225 is an apocalyptic number.

25851816225 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

25851816225 is the 160785-th square number.

25851816225 is the 80393-rd centered octagonal number.

It is an amenable number.

25851816225 is a deficient number, since it is larger than the sum of its proper divisors (22351537272).

25851816225 is an frugal number, since it uses more digits than its factorization.

25851816225 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 828 (or 405 counting only the distinct ones).

The product of its digits is 384000, while the sum is 45.

The spelling of 25851816225 in words is "twenty-five billion, eight hundred fifty-one million, eight hundred sixteen thousand, two hundred twenty-five".