81788905 has 8 divisors (see below), whose sum is σ = 107069184. Its totient is φ = 59482800.

The previous prime is 81788867. The next prime is 81788923. The reversal of 81788905 is 50988718.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 81788905 - 2⁹ = 81788393 is a prime.

It is a Duffinian number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 743481 + ... + 743590.

It is an arithmetic number, because the mean of its divisors is an integer number (13383648).

Almost surely, 2^81788905 is an apocalyptic number.

It is an amenable number.

81788905 is a deficient number, since it is larger than the sum of its proper divisors (25280279).

81788905 is a wasteful number, since it uses less digits than its factorization.

81788905 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1487087.

The product of its (nonzero) digits is 161280, while the sum is 46.

The square root of 81788905 is about 9043.7218555194. The cubic root of 81788905 is about 434.0750240168.

The spelling of 81788905 in words is "eighty-one million, seven hundred eighty-eight thousand, nine hundred five".