81633210 has 64 divisors (see below), whose sum is σ = 205832448. Its totient is φ = 20680704.

The previous prime is 81633193. The next prime is 81633257. The reversal of 81633210 is 1233618.

It is a Curzon number.

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 132864 + ... + 133476.

It is an arithmetic number, because the mean of its divisors is an integer number (3216132).

Almost surely, 2^81633210 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 81633210, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (102916224).

81633210 is an abundant number, since it is smaller than the sum of its proper divisors (124199238).

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

81633210 is a wasteful number, since it uses less digits than its factorization.

81633210 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 839.

The product of its (nonzero) digits is 864, while the sum is 24.

The square root of 81633210 is about 9035.1098499133. The cubic root of 81633210 is about 433.7994110813.

Adding to 81633210 its reverse (1233618), we get a palindrome (82866828).

The spelling of 81633210 in words is "eighty-one million, six hundred thirty-three thousand, two hundred ten".