81784881 has 12 divisors (see below), whose sum is σ = 118285440. Its totient is φ = 54453240.

The previous prime is 81784861. The next prime is 81784889. The reversal of 81784881 is 18848718.

It is not a de Polignac number, because 81784881 - 2⁶ = 81784817 is a prime.

It is a super-2 number, since 2×81784881² = 13377533520368322, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (81784889) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 2136 + ... + 12966.

It is an arithmetic number, because the mean of its divisors is an integer number (9857120).

Almost surely, 2^81784881 is an apocalyptic number.

It is an amenable number.

81784881 is a deficient number, since it is larger than the sum of its proper divisors (36500559).

81784881 is a wasteful number, since it uses less digits than its factorization.

81784881 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 11676 (or 11673 counting only the distinct ones).

The product of its digits is 114688, while the sum is 45.

The square root of 81784881 is about 9043.4993780063. The cubic root of 81784881 is about 434.0679050947.

The spelling of 81784881 in words is "eighty-one million, seven hundred eighty-four thousand, eight hundred eighty-one".