81994719 has 8 divisors (see below), whose sum is σ = 111179520. Its totient is φ = 53736536.

The previous prime is 81994691. The next prime is 81994727. The reversal of 81994719 is 91749918.

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 81994719 - 2⁸ = 81994463 is a prime.

It is a super-2 number, since 2×81994719² = 13446267887777922, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81994739) 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, 231447 + ... + 231800.

It is an arithmetic number, because the mean of its divisors is an integer number (13897440).

Almost surely, 2^81994719 is an apocalyptic number.

81994719 is a deficient number, since it is larger than the sum of its proper divisors (29184801).

81994719 is a wasteful number, since it uses less digits than its factorization.

81994719 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 463309.

The product of its digits is 163296, while the sum is 48.

The square root of 81994719 is about 9055.0935389978. The cubic root of 81994719 is about 434.4388218698.

The spelling of 81994719 in words is "eighty-one million, nine hundred ninety-four thousand, seven hundred nineteen".