81216516 has 12 divisors (see below), whose sum is σ = 189505232. Its totient is φ = 27072168.

The previous prime is 81216493. The next prime is 81216521. The reversal of 81216516 is 61561218.

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

It is a super-2 number, since 2×81216516² = 13192244942356512, which contains 22 as substring.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 3384010 + ... + 3384033.

Almost surely, 2^81216516 is an apocalyptic number.

It is an amenable number.

81216516 is an abundant number, since it is smaller than the sum of its proper divisors (108288716).

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

81216516 is a wasteful number, since it uses less digits than its factorization.

81216516 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6768050 (or 6768048 counting only the distinct ones).

The product of its digits is 2880, while the sum is 30.

The square root of 81216516 is about 9012.0206391242. The cubic root of 81216516 is about 433.0600467514.

The spelling of 81216516 in words is "eighty-one million, two hundred sixteen thousand, five hundred sixteen".