81128250 has 256 divisors, whose sum is σ = 274959360. Its totient is φ = 17280000.

The previous prime is 81128239. The next prime is 81128261. The reversal of 81128250 is 5282118.

It is an interprime number because it is at equal distance from previous prime (81128239) and next prime (81128261).

It is a hoax number, since the sum of its digits (27) coincides with the sum of the digits of its distinct prime factors.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is an unprimeable number.

It is a polite number, since it can be written in 127 ways as a sum of consecutive naturals, for example, 803200 + ... + 803300.

It is an arithmetic number, because the mean of its divisors is an integer number (1074060).

Almost surely, 2^81128250 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 81128250, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (137479680).

81128250 is an abundant number, since it is smaller than the sum of its proper divisors (193831110).

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

81128250 is a wasteful number, since it uses less digits than its factorization.

81128250 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 151 (or 135 counting only the distinct ones).

The product of its (nonzero) digits is 1280, while the sum is 27.

The square root of 81128250 is about 9007.1221819180. The cubic root of 81128250 is about 432.9031068588.

The spelling of 81128250 in words is "eighty-one million, one hundred twenty-eight thousand, two hundred fifty".