81840210 has 64 divisors (see below), whose sum is σ = 217043712. Its totient is φ = 19644416.

The previous prime is 81840203. The next prime is 81840211. The reversal of 81840210 is 1204818.

It is not an unprimeable number, because it can be changed into a prime (81840211) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 8242 + ... + 15218.

It is an arithmetic number, because the mean of its divisors is an integer number (3391308).

Almost surely, 2^81840210 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 81840210, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (108521856).

81840210 is an abundant number, since it is smaller than the sum of its proper divisors (135203502).

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

81840210 is a wasteful number, since it uses less digits than its factorization.

81840210 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7027.

The product of its (nonzero) digits is 512, while the sum is 24.

The square root of 81840210 is about 9046.5579089508. The cubic root of 81840210 is about 434.1657680451.

The spelling of 81840210 in words is "eighty-one million, eight hundred forty thousand, two hundred ten".