81816080 has 20 divisors (see below), whose sum is σ = 190222572. Its totient is φ = 32726400.

The previous prime is 81816079. The next prime is 81816089. The reversal of 81816080 is 8061818.

It is a happy number.

It can be written as a sum of positive squares in 2 ways, for example, as 62031376 + 19784704 = 7876^2 + 4448^2 .

It is a tau number, because it is divible by the number of its divisors (20).

It is not an unprimeable number, because it can be changed into a prime (81816089) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 511271 + ... + 511430.

Almost surely, 2^81816080 is an apocalyptic number.

81816080 is a gapful number since it is divisible by the number (80) formed by its first and last digit.

It is an amenable number.

81816080 is an abundant number, since it is smaller than the sum of its proper divisors (108406492).

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

81816080 is a wasteful number, since it uses less digits than its factorization.

81816080 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1022714 (or 1022708 counting only the distinct ones).

The product of its (nonzero) digits is 3072, while the sum is 32.

The square root of 81816080 is about 9045.2241542153. The cubic root of 81816080 is about 434.1230936280.

Adding to 81816080 its reverse (8061818), we get a palindrome (89877898).

The spelling of 81816080 in words is "eighty-one million, eight hundred sixteen thousand, eighty".