81778528 has 24 divisors (see below), whose sum is σ = 173387088. Its totient is φ = 37743744.

The previous prime is 81778519. The next prime is 81778553. The reversal of 81778528 is 82587718.

It is a happy number.

It is a Smith number, since the sum of its digits (46) coincides with the sum of the digits of its prime factors.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 97876 + ... + 98707.

It is an arithmetic number, because the mean of its divisors is an integer number (7224462).

Almost surely, 2^81778528 is an apocalyptic number.

It is an amenable number.

81778528 is an abundant number, since it is smaller than the sum of its proper divisors (91608560).

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

81778528 is a wasteful number, since it uses less digits than its factorization.

81778528 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 196606 (or 196598 counting only the distinct ones).

The product of its digits is 250880, while the sum is 46.

The square root of 81778528 is about 9043.1481244089. The cubic root of 81778528 is about 434.0566654263.

The spelling of 81778528 in words is "eighty-one million, seven hundred seventy-eight thousand, five hundred twenty-eight".