81616597 has 4 divisors (see below), whose sum is σ = 82954636. Its totient is φ = 80278560.

The previous prime is 81616589. The next prime is 81616621. The reversal of 81616597 is 79561618.

It is a happy number.

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

It can be written as a sum of positive squares in 2 ways, for example, as 36108081 + 45508516 = 6009^2 + 6746^2 .

It is a cyclic number.

It is not a de Polignac number, because 81616597 - 2³ = 81616589 is a prime.

It is a super-2 number, since 2×81616597² = 13322537811720818, 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 (81616547) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 668928 + ... + 669049.

It is an arithmetic number, because the mean of its divisors is an integer number (20738659).

Almost surely, 2^81616597 is an apocalyptic number.

It is an amenable number.

81616597 is a deficient number, since it is larger than the sum of its proper divisors (1338039).

81616597 is a wasteful number, since it uses less digits than its factorization.

81616597 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1338038.

The product of its digits is 90720, while the sum is 43.

The square root of 81616597 is about 9034.1904451921. The cubic root of 81616597 is about 433.7699818881.

The spelling of 81616597 in words is "eighty-one million, six hundred sixteen thousand, five hundred ninety-seven".