81519719 has 4 divisors (see below), whose sum is σ = 81569400. Its totient is φ = 81470040.

The previous prime is 81519689. The next prime is 81519721. The reversal of 81519719 is 91791518.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 81519719 - 2⁸ = 81519463 is a prime.

It is a super-2 number, since 2×81519719² = 13290929171677922, 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 (81519799) 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, 22292 + ... + 25689.

It is an arithmetic number, because the mean of its divisors is an integer number (20392350).

Almost surely, 2^81519719 is an apocalyptic number.

81519719 is a deficient number, since it is larger than the sum of its proper divisors (49681).

81519719 is a wasteful number, since it uses less digits than its factorization.

81519719 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 49680.

The product of its digits is 22680, while the sum is 41.

The square root of 81519719 is about 9028.8271109818. The cubic root of 81519719 is about 433.5982872096.

The spelling of 81519719 in words is "eighty-one million, five hundred nineteen thousand, seven hundred nineteen".