81389880 has 512 divisors, whose sum is σ = 348364800. Its totient is φ = 16588800.

The previous prime is 81389873. The next prime is 81389953. The reversal of 81389880 is 8898318.

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

It is a congruent number.

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, 2625465 + ... + 2625495.

It is an arithmetic number, because the mean of its divisors is an integer number (680400).

Almost surely, 2^81389880 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 81389880, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (174182400).

81389880 is an abundant number, since it is smaller than the sum of its proper divisors (266974920).

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

81389880 is a wasteful number, since it uses less digits than its factorization.

81389880 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 92 (or 82 counting only the distinct ones).

The product of its (nonzero) digits is 110592, while the sum is 45.

The square root of 81389880 is about 9021.6339983398. The cubic root of 81389880 is about 433.3679630445.

The spelling of 81389880 in words is "eighty-one million, three hundred eighty-nine thousand, eight hundred eighty".