81909060 has 96 divisors (see below), whose sum is σ = 245089152. Its totient is φ = 20367360.

The previous prime is 81909011. The next prime is 81909071. The reversal of 81909060 is 6090918.

It is a happy number.

It is a super-2 number, since 2×81909060² = 13418188220167200, which contains 22 as substring.

It is a hoax number, since the sum of its digits (33) coincides with the sum of the digits of its distinct prime factors.

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, 133314 + ... + 133926.

It is an arithmetic number, because the mean of its divisors is an integer number (2553012).

Almost surely, 2^81909060 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 81909060, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (122544576).

81909060 is an abundant number, since it is smaller than the sum of its proper divisors (163180092).

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

81909060 is a wasteful number, since it uses less digits than its factorization.

81909060 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 773 (or 771 counting only the distinct ones).

The product of its (nonzero) digits is 3888, while the sum is 33.

The square root of 81909060 is about 9050.3624236823. The cubic root of 81909060 is about 434.2874846378.

Adding to 81909060 its reverse (6090918), we get a palindrome (87999978).

The spelling of 81909060 in words is "eighty-one million, nine hundred nine thousand, sixty".