81778800 has 120 divisors (see below), whose sum is σ = 273446784. Its totient is φ = 20852480.

The previous prime is 81778759. The next prime is 81778813. The reversal of 81778800 is 887718.

It is a happy number.

It is a tau number, because it is divible by the number of its divisors (120).

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, 26119 + ... + 29081.

Almost surely, 2^81778800 is an apocalyptic number.

81778800 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 81778800, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (136723392).

81778800 is an abundant number, since it is smaller than the sum of its proper divisors (191667984).

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

81778800 is a wasteful number, since it uses less digits than its factorization.

81778800 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3007 (or 2996 counting only the distinct ones).

The product of its (nonzero) digits is 25088, while the sum is 39.

The square root of 81778800 is about 9043.1631634069. The cubic root of 81778800 is about 434.0571466581.

The spelling of 81778800 in words is "eighty-one million, seven hundred seventy-eight thousand, eight hundred".