81616659 has 8 divisors (see below), whose sum is σ = 109002192. Its totient is φ = 54321120.

The previous prime is 81616657. The next prime is 81616679. The reversal of 81616659 is 95661618.

It is a happy number.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 81616659 - 2¹ = 81616657 is a prime.

It is a super-2 number, since 2×81616659² = 13322558052644562, which contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 81616659.

It is not an unprimeable number, because it can be changed into a prime (81616651) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 20352 + ... + 24029.

It is an arithmetic number, because the mean of its divisors is an integer number (13625274).

Almost surely, 2^81616659 is an apocalyptic number.

81616659 is a deficient number, since it is larger than the sum of its proper divisors (27385533).

81616659 is a wasteful number, since it uses less digits than its factorization.

81616659 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 44997.

The product of its digits is 77760, while the sum is 42.

The square root of 81616659 is about 9034.1938766002. The cubic root of 81616659 is about 433.7700917257.

The spelling of 81616659 in words is "eighty-one million, six hundred sixteen thousand, six hundred fifty-nine".