81369181 has 8 divisors (see below), whose sum is σ = 82871928. Its totient is φ = 79872000.

The previous prime is 81369161. The next prime is 81369199. The reversal of 81369181 is 18196318.

It can be written as a sum of positive squares in 4 ways, for example, as 5522500 + 75846681 = 2350^2 + 8709^2 .

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

It is a cyclic number.

It is not a de Polignac number, because 81369181 - 2⁵ = 81369149 is a prime.

It is a super-2 number, since 2×81369181² = 13241887233221522, which contains 22 as substring.

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 81369181.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81369121) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 38061 + ... + 40141.

It is an arithmetic number, because the mean of its divisors is an integer number (10358991).

Almost surely, 2^81369181 is an apocalyptic number.

It is an amenable number.

81369181 is a deficient number, since it is larger than the sum of its proper divisors (1502747).

81369181 is a wasteful number, since it uses less digits than its factorization.

81369181 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2783.

The product of its digits is 10368, while the sum is 37.

The square root of 81369181 is about 9020.4867385302. The cubic root of 81369181 is about 433.3312220147.

The spelling of 81369181 in words is "eighty-one million, three hundred sixty-nine thousand, one hundred eighty-one".