81504775 has 36 divisors (see below), whose sum is σ = 116503704. Its totient is φ = 56088000.

The previous prime is 81504767. The next prime is 81504781. The reversal of 81504775 is 57740518.

It is not a de Polignac number, because 81504775 - 2³ = 81504767 is a prime.

It is a Duffinian number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 35 ways as a sum of consecutive naturals, for example, 98865 + ... + 99685.

It is an arithmetic number, because the mean of its divisors is an integer number (3236214).

Almost surely, 2^81504775 is an apocalyptic number.

81504775 is a deficient number, since it is larger than the sum of its proper divisors (34998929).

81504775 is a wasteful number, since it uses less digits than its factorization.

81504775 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 880 (or 856 counting only the distinct ones).

The product of its (nonzero) digits is 39200, while the sum is 37.

The square root of 81504775 is about 9027.9995015507. Note that the first 3 decimals coincide. The cubic root of 81504775 is about 433.5717901900.

The spelling of 81504775 in words is "eighty-one million, five hundred four thousand, seven hundred seventy-five".