81858780 has 72 divisors (see below), whose sum is σ = 249709824. Its totient is φ = 21705600.

The previous prime is 81858743. The next prime is 81858781. The reversal of 81858780 is 8785818.

81858780 = T₂₅ + T₂₆ + ... + T₇₈₈.

It is a happy number.

It is a Harshad number since it is a multiple of its sum of digits (45).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81858781) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 33190 + ... + 35570.

It is an arithmetic number, because the mean of its divisors is an integer number (3468192).

Almost surely, 2^81858780 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 81858780, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (124854912).

81858780 is an abundant number, since it is smaller than the sum of its proper divisors (167851044).

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

81858780 is a wasteful number, since it uses less digits than its factorization.

81858780 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2587 (or 2582 counting only the distinct ones).

The product of its (nonzero) digits is 143360, while the sum is 45.

The square root of 81858780 is about 9047.5842079530. The cubic root of 81858780 is about 434.1986037730.

The spelling of 81858780 in words is "eighty-one million, eight hundred fifty-eight thousand, seven hundred eighty".