81683719 has 4 divisors (see below), whose sum is σ = 87967096. Its totient is φ = 75400344.

The previous prime is 81683711. The next prime is 81683731. The reversal of 81683719 is 91738618.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 91738618 = 2 ⋅45869309.

It is a cyclic number.

It is not a de Polignac number, because 81683719 - 2³ = 81683711 is a prime.

It is a super-2 number, since 2×81683719² = 13344459899341922, 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 (81683711) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 3141669 + ... + 3141694.

It is an arithmetic number, because the mean of its divisors is an integer number (21991774).

Almost surely, 2^81683719 is an apocalyptic number.

81683719 is a deficient number, since it is larger than the sum of its proper divisors (6283377).

81683719 is a wasteful number, since it uses less digits than its factorization.

81683719 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6283376.

The product of its digits is 72576, while the sum is 43.

The square root of 81683719 is about 9037.9045690912. The cubic root of 81683719 is about 433.8888610207. Note that the first 4 decimals are identical.

The spelling of 81683719 in words is "eighty-one million, six hundred eighty-three thousand, seven hundred nineteen".