81902533566 has 64 divisors (see below), whose sum is σ = 192426513408. Its totient is φ = 22755952128.

The previous prime is 81902533561. The next prime is 81902533621. The reversal of 81902533566 is 66533520918.

It is a Smith number, since the sum of its digits (48) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81902533561) 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, 88735 + ... + 414341.

It is an arithmetic number, because the mean of its divisors is an integer number (3006664272).

Almost surely, 2^81902533566 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 81902533566, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (96213256704).

81902533566 is an abundant number, since it is smaller than the sum of its proper divisors (110523979842).

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

81902533566 is a wasteful number, since it uses less digits than its factorization.

81902533566 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 325785.

The product of its (nonzero) digits is 1166400, while the sum is 48.

The spelling of 81902533566 in words is "eighty-one billion, nine hundred two million, five hundred thirty-three thousand, five hundred sixty-six".