81611919 has 12 divisors (see below), whose sum is σ = 118677000. Its totient is φ = 54041904.

The previous prime is 81611911. The next prime is 81611941. The reversal of 81611919 is 91911618.

It is not a de Polignac number, because 81611919 - 2³ = 81611911 is a prime.

It is a super-2 number, since 2×81611919² = 13321010645725122, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81611911) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 29089 + ... + 31770.

It is an arithmetic number, because the mean of its divisors is an integer number (9889750).

Almost surely, 2^81611919 is an apocalyptic number.

81611919 is a deficient number, since it is larger than the sum of its proper divisors (37065081).

81611919 is a wasteful number, since it uses less digits than its factorization.

81611919 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 61014 (or 61011 counting only the distinct ones).

The product of its digits is 3888, while the sum is 36.

The square root of 81611919 is about 9033.9315361586. The cubic root of 81611919 is about 433.7616942978.

The spelling of 81611919 in words is "eighty-one million, six hundred eleven thousand, nine hundred nineteen".