81918516 has 12 divisors (see below), whose sum is σ = 191143232. Its totient is φ = 27306168.

The previous prime is 81918511. The next prime is 81918521. The reversal of 81918516 is 61581918.

It is an interprime number because it is at equal distance from previous prime (81918511) and next prime (81918521).

It is a tau number, because it is divible by the number of its divisors (12).

It is a hoax number, since the sum of its digits (39) coincides with the sum of the digits of its distinct prime factors.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81918511) 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, 3413260 + ... + 3413283.

Almost surely, 2^81918516 is an apocalyptic number.

It is an amenable number.

81918516 is an abundant number, since it is smaller than the sum of its proper divisors (109224716).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

81918516 is a wasteful number, since it uses less digits than its factorization.

81918516 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6826550 (or 6826548 counting only the distinct ones).

The product of its digits is 17280, while the sum is 39.

The square root of 81918516 is about 9050.8848186241. The cubic root of 81918516 is about 434.3041961161.

The spelling of 81918516 in words is "eighty-one million, nine hundred eighteen thousand, five hundred sixteen".