81513986 has 8 divisors (see below), whose sum is σ = 125253324. Its totient is φ = 39762880.

The previous prime is 81513979. The next prime is 81513989. The reversal of 81513986 is 68931518.

It can be written as a sum of positive squares in 2 ways, for example, as 80658361 + 855625 = 8981^2 + 925^2 .

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

It is a Harshad number since it is a multiple of its sum of digits (41).

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (81513989) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 496955 + ... + 497118.

Almost surely, 2^81513986 is an apocalyptic number.

81513986 is a deficient number, since it is larger than the sum of its proper divisors (43739338).

81513986 is a wasteful number, since it uses less digits than its factorization.

81513986 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 994116.

The product of its digits is 51840, while the sum is 41.

The square root of 81513986 is about 9028.5096223020. The cubic root of 81513986 is about 433.5881224818.

The spelling of 81513986 in words is "eighty-one million, five hundred thirteen thousand, nine hundred eighty-six".