81755905 has 16 divisors (see below), whose sum is σ = 122315904. Its totient is φ = 50964480.

The previous prime is 81755893. The next prime is 81755909. The reversal of 81755905 is 50955718.

It is not a de Polignac number, because 81755905 - 2¹¹ = 81753857 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (81755909) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 105792 + ... + 106561.

It is an arithmetic number, because the mean of its divisors is an integer number (7644744).

Almost surely, 2^81755905 is an apocalyptic number.

It is an amenable number.

81755905 is a deficient number, since it is larger than the sum of its proper divisors (40559999).

81755905 is a wasteful number, since it uses less digits than its factorization.

81755905 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 212376.

The product of its (nonzero) digits is 63000, while the sum is 40.

The square root of 81755905 is about 9041.8972013621. The cubic root of 81755905 is about 434.0166362980.

The spelling of 81755905 in words is "eighty-one million, seven hundred fifty-five thousand, nine hundred five".