81701840 has 80 divisors (see below), whose sum is σ = 208647360. Its totient is φ = 29506560.

The previous prime is 81701831. The next prime is 81701861. The reversal of 81701840 is 4810718.

It is a tau number, because it is divible by the number of its divisors (80).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 199556 + ... + 199964.

It is an arithmetic number, because the mean of its divisors is an integer number (2608092).

Almost surely, 2^81701840 is an apocalyptic number.

81701840 is a gapful number since it is divisible by the number (80) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 81701840, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (104323680).

81701840 is an abundant number, since it is smaller than the sum of its proper divisors (126945520).

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

81701840 is a wasteful number, since it uses less digits than its factorization.

81701840 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 660 (or 654 counting only the distinct ones).

The product of its (nonzero) digits is 1792, while the sum is 29.

The square root of 81701840 is about 9038.9070135719. The cubic root of 81701840 is about 433.9209437858.

The spelling of 81701840 in words is "eighty-one million, seven hundred one thousand, eight hundred forty".