81018719 has 16 divisors (see below), whose sum is σ = 90383040. Its totient is φ = 72230400.

The previous prime is 81018703. The next prime is 81018731. The reversal of 81018719 is 91781018.

It is a cyclic number.

It is not a de Polignac number, because 81018719 - 2⁴ = 81018703 is a prime.

It is a super-2 number, since 2×81018719² = 13128065656801922, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81018019) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 41669 + ... + 43569.

It is an arithmetic number, because the mean of its divisors is an integer number (5648940).

Almost surely, 2^81018719 is an apocalyptic number.

81018719 is a deficient number, since it is larger than the sum of its proper divisors (9364321).

81018719 is a wasteful number, since it uses less digits than its factorization.

81018719 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2050.

The product of its (nonzero) digits is 4032, while the sum is 35.

The square root of 81018719 is about 9001.0398843689. The cubic root of 81018719 is about 432.7081987345.

The spelling of 81018719 in words is "eighty-one million, eighteen thousand, seven hundred nineteen".