81788889 has 48 divisors (see below), whose sum is σ = 138098688. Its totient is φ = 42674688.

The previous prime is 81788867. The next prime is 81788923. The reversal of 81788889 is 98888718.

81788889 is nontrivially palindromic in base 2.

It is not a de Polignac number, because 81788889 - 2⁷ = 81788761 is a prime.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (81788089) by changing a digit.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 242529 + ... + 242865.

It is an arithmetic number, because the mean of its divisors is an integer number (2877056).

Almost surely, 2^81788889 is an apocalyptic number.

It is an amenable number.

81788889 is a deficient number, since it is larger than the sum of its proper divisors (56309799).

81788889 is a wasteful number, since it uses less digits than its factorization.

81788889 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 494 (or 487 counting only the distinct ones).

The product of its digits is 2064384, while the sum is 57.

The square root of 81788889 is about 9043.7209709278. The cubic root of 81788889 is about 434.0749957114.

The spelling of 81788889 in words is "eighty-one million, seven hundred eighty-eight thousand, eight hundred eighty-nine".