81869766 has 32 divisors (see below), whose sum is σ = 180309888. Its totient is φ = 24575040.

The previous prime is 81869761. The next prime is 81869783. The reversal of 81869766 is 66796818.

It is a happy number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81869761) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 1266 + ... + 12858.

It is an arithmetic number, because the mean of its divisors is an integer number (5634684).

Almost surely, 2^81869766 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 81869766, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (90154944).

81869766 is an abundant number, since it is smaller than the sum of its proper divisors (98440122).

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

81869766 is a wasteful number, since it uses less digits than its factorization.

81869766 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 11716.

The product of its digits is 870912, while the sum is 51.

The square root of 81869766 is about 9048.1913109748. The cubic root of 81869766 is about 434.2180270305.

The spelling of 81869766 in words is "eighty-one million, eight hundred sixty-nine thousand, seven hundred sixty-six".