81969804 has 72 divisors (see below), whose sum is σ = 239715840. Its totient is φ = 23131872.

The previous prime is 81969799. The next prime is 81969809. The reversal of 81969804 is 40896918.

It is an interprime number because it is at equal distance from previous prime (81969799) and next prime (81969809).

It is a hoax number, since the sum of its digits (45) coincides with the sum of the digits of its distinct prime factors.

It is a self number, because there is not a number n which added to its sum of digits gives 81969804.

It is not an unprimeable number, because it can be changed into a prime (81969809) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 18957 + ... + 22875.

Almost surely, 2^81969804 is an apocalyptic number.

81969804 is a gapful number since it is divisible by the number (84) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 81969804, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (119857920).

81969804 is an abundant number, since it is smaller than the sum of its proper divisors (157746036).

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

81969804 is a wasteful number, since it uses less digits than its factorization.

81969804 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4019 (or 4014 counting only the distinct ones).

The product of its (nonzero) digits is 124416, while the sum is 45.

The square root of 81969804 is about 9053.7176894356. The cubic root of 81969804 is about 434.3948144025.

The spelling of 81969804 in words is "eighty-one million, nine hundred sixty-nine thousand, eight hundred four".