81712890 has 96 divisors (see below), whose sum is σ = 247852800. Its totient is φ = 18670176.

The previous prime is 81712879. The next prime is 81712903. The reversal of 81712890 is 9821718.

It is a hoax number, since the sum of its digits (36) coincides with the sum of the digits of its distinct prime factors.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 29547 + ... + 32193.

It is an arithmetic number, because the mean of its divisors is an integer number (2581800).

Almost surely, 2^81712890 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 81712890, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (123926400).

81712890 is an abundant number, since it is smaller than the sum of its proper divisors (166139910).

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

81712890 is a wasteful number, since it uses less digits than its factorization.

81712890 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2681 (or 2664 counting only the distinct ones).

The product of its (nonzero) digits is 8064, while the sum is 36.

The square root of 81712890 is about 9039.5182393754. The cubic root of 81712890 is about 433.9405051987.

The spelling of 81712890 in words is "eighty-one million, seven hundred twelve thousand, eight hundred ninety".