81873816 has 24 divisors (see below), whose sum is σ = 204795420. Its totient is φ = 27276496.

The previous prime is 81873797. The next prime is 81873829. The reversal of 81873816 is 61837818.

It is a tau number, because it is divible by the number of its divisors (24).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 43405 + ... + 45251.

Almost surely, 2^81873816 is an apocalyptic number.

It is an amenable number.

81873816 is an abundant number, since it is smaller than the sum of its proper divisors (122921604).

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

81873816 is an equidigital number, since it uses as much as digits as its factorization.

81873816 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3703 (or 1852 counting only the distinct ones).

The product of its digits is 64512, while the sum is 42.

The square root of 81873816 is about 9048.4151098411. The cubic root of 81873816 is about 434.2251869956.

The spelling of 81873816 in words is "eighty-one million, eight hundred seventy-three thousand, eight hundred sixteen".