81778872 has 64 divisors (see below), whose sum is σ = 238648320. Its totient is φ = 22866048.

The previous prime is 81778871. The next prime is 81778883. The reversal of 81778872 is 27887718.

It is a nude number because it is divisible by every one of its digits.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81778871) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 2718 + ... + 13074.

It is an arithmetic number, because the mean of its divisors is an integer number (3728880).

Almost surely, 2^81778872 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 81778872, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (119324160).

81778872 is an abundant number, since it is smaller than the sum of its proper divisors (156869448).

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

81778872 is a wasteful number, since it uses less digits than its factorization.

81778872 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10420 (or 10416 counting only the distinct ones).

The product of its digits is 351232, while the sum is 48.

The square root of 81778872 is about 9043.1671443140. The cubic root of 81778872 is about 434.0572740428.

The spelling of 81778872 in words is "eighty-one million, seven hundred seventy-eight thousand, eight hundred seventy-two".