81804501 has 6 divisors (see below), whose sum is σ = 118162070. Its totient is φ = 54536328.

The previous prime is 81804473. The next prime is 81804509. The reversal of 81804501 is 10540818.

81804501 is a `hidden beast` number, since 81 + 80 + 4 + 501 = 666.

It can be written as a sum of positive squares in only one way, i.e., 55487601 + 26316900 = 7449^2 + 5130^2 .

It is not a de Polignac number, because 81804501 - 2¹⁷ = 81673429 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81804509) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 4544686 + ... + 4544703.

Almost surely, 2^81804501 is an apocalyptic number.

It is an amenable number.

81804501 is a deficient number, since it is larger than the sum of its proper divisors (36357569).

81804501 is a wasteful number, since it uses less digits than its factorization.

81804501 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 9089395 (or 9089392 counting only the distinct ones).

The product of its (nonzero) digits is 1280, while the sum is 27.

The square root of 81804501 is about 9044.5840700388. The cubic root of 81804501 is about 434.1026129415.

The spelling of 81804501 in words is "eighty-one million, eight hundred four thousand, five hundred one".