81969719 has 4 divisors (see below), whose sum is σ = 88275096. Its totient is φ = 75664344.

The previous prime is 81969707. The next prime is 81969793. The reversal of 81969719 is 91796918.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 91796918 = 2 ⋅45898459.

It is a cyclic number.

It is not a de Polignac number, because 81969719 - 2²⁰ = 80921143 is a prime.

It is a super-2 number, since 2×81969719² = 13438069665877922, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81969799) 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, 3152669 + ... + 3152694.

It is an arithmetic number, because the mean of its divisors is an integer number (22068774).

Almost surely, 2^81969719 is an apocalyptic number.

81969719 is a deficient number, since it is larger than the sum of its proper divisors (6305377).

81969719 is a wasteful number, since it uses less digits than its factorization.

81969719 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6305376.

The product of its digits is 244944, while the sum is 50.

The square root of 81969719 is about 9053.7129952302. The cubic root of 81969719 is about 434.3946642513.

The spelling of 81969719 in words is "eighty-one million, nine hundred sixty-nine thousand, seven hundred nineteen".