81428256 has 216 divisors, whose sum is σ = 287763840. Its totient is φ = 21385728.

The previous prime is 81428239. The next prime is 81428287. The reversal of 81428256 is 65282418.

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a self number, because there is not a number n which added to its sum of digits gives 81428256.

It is an unprimeable number.

It is a polite number, since it can be written in 35 ways as a sum of consecutive naturals, for example, 340585 + ... + 340823.

It is an arithmetic number, because the mean of its divisors is an integer number (1332240).

Almost surely, 2^81428256 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 81428256, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (143881920).

81428256 is an abundant number, since it is smaller than the sum of its proper divisors (206335584).

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

81428256 is a wasteful number, since it uses less digits than its factorization.

81428256 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 288 (or 264 counting only the distinct ones).

The product of its digits is 30720, while the sum is 36.

The square root of 81428256 is about 9023.7606351233. The cubic root of 81428256 is about 433.4360645323.

The spelling of 81428256 in words is "eighty-one million, four hundred twenty-eight thousand, two hundred fifty-six".