81618291 has 12 divisors (see below), whose sum is σ = 118226160. Its totient is φ = 54258480.

The previous prime is 81618259. The next prime is 81618293. The reversal of 81618291 is 19281618.

It is not a de Polignac number, because 81618291 - 2⁵ = 81618259 is a prime.

It is a hoax number, since the sum of its digits (36) coincides with the sum of the digits of its distinct prime factors.

It is not an unprimeable number, because it can be changed into a prime (81618293) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 9400 + ... + 15861.

It is an arithmetic number, because the mean of its divisors is an integer number (9852180).

Almost surely, 2^81618291 is an apocalyptic number.

81618291 is a deficient number, since it is larger than the sum of its proper divisors (36607869).

81618291 is a wasteful number, since it uses less digits than its factorization.

81618291 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 25626 (or 25623 counting only the distinct ones).

The product of its digits is 6912, while the sum is 36.

The square root of 81618291 is about 9034.2841996475. The cubic root of 81618291 is about 433.7729829168.

The spelling of 81618291 in words is "eighty-one million, six hundred eighteen thousand, two hundred ninety-one".