81910400 has 192 divisors, whose sum is σ = 239047200. Its totient is φ = 27340800.

The previous prime is 81910393. The next prime is 81910417. The reversal of 81910400 is 401918.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 457511 + ... + 457689.

Almost surely, 2^81910400 is an apocalyptic number.

81910400 is a gapful number since it is divisible by the number (80) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 81910400, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (119523600).

81910400 is an abundant number, since it is smaller than the sum of its proper divisors (157136800).

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

81910400 is a wasteful number, since it uses less digits than its factorization.

81910400 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 227 (or 210 counting only the distinct ones).

The product of its (nonzero) digits is 288, while the sum is 23.

The square root of 81910400 is about 9050.4364535640. The cubic root of 81910400 is about 434.2898528823.

The spelling of 81910400 in words is "eighty-one million, nine hundred ten thousand, four hundred".