81600400 has 120 divisors (see below), whose sum is σ = 226703744. Its totient is φ = 27648000.

The previous prime is 81600361. The next prime is 81600419. The reversal of 81600400 is 400618.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 422704 + ... + 422896.

Almost surely, 2^81600400 is an apocalyptic number.

81600400 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 81600400, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (113351872).

81600400 is an abundant number, since it is smaller than the sum of its proper divisors (145103344).

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

81600400 is a wasteful number, since it uses less digits than its factorization.

81600400 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 369 (or 358 counting only the distinct ones).

The product of its (nonzero) digits is 192, while the sum is 19.

The square root of 81600400 is about 9033.2939728540. The cubic root of 81600400 is about 433.7412857753.

The spelling of 81600400 in words is "eighty-one million, six hundred thousand, four hundred".