81179881 has 2 divisors, whose sum is σ = 81179882. Its totient is φ = 81179880.

The previous prime is 81179873. The next prime is 81179899. The reversal of 81179881 is 18897118.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 58293225 + 22886656 = 7635^2 + 4784^2 .

It is a cyclic number.

It is not a de Polignac number, because 81179881 - 2³ = 81179873 is a prime.

It is a super-2 number, since 2×81179881² = 13180346158348322, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (81179831) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40589940 + 40589941.

It is an arithmetic number, because the mean of its divisors is an integer number (40589941).

Almost surely, 2^81179881 is an apocalyptic number.

It is an amenable number.

81179881 is a deficient number, since it is larger than the sum of its proper divisors (1).

81179881 is an equidigital number, since it uses as much as digits as its factorization.

81179881 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 32256, while the sum is 43.

The square root of 81179881 is about 9009.9878468287. The cubic root of 81179881 is about 432.9949223092.

The spelling of 81179881 in words is "eighty-one million, one hundred seventy-nine thousand, eight hundred eighty-one".