81785163555225 has 189 divisors, whose sum is σ = 164678733593607. Its totient is φ = 40255651537920.

The previous prime is 81785163555197. The next prime is 81785163555253. The reversal of 81785163555225 is 52255536158718.

The square root of 81785163555225 is 9043515.

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

81785163555225 is a `hidden beast` number, since 8 + 1 + 7 + 8 + 51 + 6 + 3 + 5 + 552 + 25 = 666.

It is an interprime number because it is at equal distance from previous prime (81785163555197) and next prime (81785163555253).

It can be written as a sum of positive squares in 13 ways, for example, as 70193916868761 + 11591246686464 = 8378181^2 + 3404592^2 .

It is not a de Polignac number, because 81785163555225 - 2⁷ = 81785163555097 is a prime.

It is a Curzon number.

It is an unprimeable number.

It is a polite number, since it can be written in 188 ways as a sum of consecutive naturals, for example, 15871366249 + ... + 15871371401.

Almost surely, 2^{81785163555225} is an apocalyptic number.

81785163555225 is the 9043515-th square number.

81785163555225 is the 4521758-th centered octagonal number.

It is an amenable number.

81785163555225 is an abundant number, since it is smaller than the sum of its proper divisors (82893570038382).

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

81785163555225 is an frugal number, since it uses more digits than its factorization.

81785163555225 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10360 (or 5174 counting only the distinct ones).

The product of its digits is 100800000, while the sum is 63.

The spelling of 81785163555225 in words is "eighty-one trillion, seven hundred eighty-five billion, one hundred sixty-three million, five hundred fifty-five thousand, two hundred twenty-five".