81936473 has 2 divisors, whose sum is σ = 81936474. Its totient is φ = 81936472.

The previous prime is 81936467. The next prime is 81936497. The reversal of 81936473 is 37463918.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 77492809 + 4443664 = 8803^2 + 2108^2 .

It is a cyclic number.

It is not a de Polignac number, because 81936473 - 2¹² = 81932377 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 81936473.

It is not a weakly prime, because it can be changed into another prime (81936403) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40968236 + 40968237.

It is an arithmetic number, because the mean of its divisors is an integer number (40968237).

Almost surely, 2^81936473 is an apocalyptic number.

It is an amenable number.

81936473 is a deficient number, since it is larger than the sum of its proper divisors (1).

81936473 is an equidigital number, since it uses as much as digits as its factorization.

81936473 is an evil number, because the sum of its binary digits is even.

The product of its digits is 108864, while the sum is 41.

The square root of 81936473 is about 9051.8767667263. The cubic root of 81936473 is about 434.3359277727.

The spelling of 81936473 in words is "eighty-one million, nine hundred thirty-six thousand, four hundred seventy-three".