81930816 has 168 divisors, whose sum is σ = 261359904. Its totient is φ = 24330240.

The previous prime is 81930757. The next prime is 81930817. The reversal of 81930816 is 61803918.

It is a super-2 number, since 2×81930816² = 13425317220851712, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (36).

It is not an unprimeable number, because it can be changed into a prime (81930817) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 424416 + ... + 424608.

Almost surely, 2^81930816 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 81930816, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (130679952).

81930816 is an abundant number, since it is smaller than the sum of its proper divisors (179429088).

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

81930816 is a wasteful number, since it uses less digits than its factorization.

81930816 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 289 (or 276 counting only the distinct ones).

The product of its (nonzero) digits is 10368, while the sum is 36.

The square root of 81930816 is about 9051.5642846969. The cubic root of 81930816 is about 434.3259318381.

The spelling of 81930816 in words is "eighty-one million, nine hundred thirty thousand, eight hundred sixteen".