81618265 has 8 divisors (see below), whose sum is σ = 98349768. Its totient is φ = 65022720.

The previous prime is 81618259. The next prime is 81618293. The reversal of 81618265 is 56281618.

It can be written as a sum of positive squares in 4 ways, for example, as 20575296 + 61042969 = 4536^2 + 7813^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 81618265 - 2⁵ = 81618233 is a prime.

It is a super-2 number, since 2×81618265² = 13323082363220450, which contains 22 as substring.

It is a Duffinian number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 32662 + ... + 35071.

It is an arithmetic number, because the mean of its divisors is an integer number (12293721).

Almost surely, 2^81618265 is an apocalyptic number.

It is an amenable number.

81618265 is a deficient number, since it is larger than the sum of its proper divisors (16731503).

81618265 is a wasteful number, since it uses less digits than its factorization.

81618265 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 67979.

The product of its digits is 23040, while the sum is 37.

The square root of 81618265 is about 9034.2827606844. The cubic root of 81618265 is about 433.7729368565.

The spelling of 81618265 in words is "eighty-one million, six hundred eighteen thousand, two hundred sixty-five".