81250820 has 72 divisors (see below), whose sum is σ = 210202776. Its totient is φ = 26213376.

The previous prime is 81250787. The next prime is 81250823. The reversal of 81250820 is 2805218.

It can be written as a sum of positive squares in 4 ways, for example, as 9746884 + 71503936 = 3122^2 + 8456^2 .

It is a self number, because there is not a number n which added to its sum of digits gives 81250820.

It is not an unprimeable number, because it can be changed into a prime (81250823) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 14222 + ... + 19098.

It is an arithmetic number, because the mean of its divisors is an integer number (2919483).

Almost surely, 2^81250820 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 81250820, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (105101388).

81250820 is an abundant number, since it is smaller than the sum of its proper divisors (128951956).

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

81250820 is a wasteful number, since it uses less digits than its factorization.

81250820 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4917 (or 4908 counting only the distinct ones).

The product of its (nonzero) digits is 1280, while the sum is 26.

The square root of 81250820 is about 9013.9236739613. The cubic root of 81250820 is about 433.1210097241.

The spelling of 81250820 in words is "eighty-one million, two hundred fifty thousand, eight hundred twenty".