81523873 has 2 divisors, whose sum is σ = 81523874. Its totient is φ = 81523872.

The previous prime is 81523853. The next prime is 81523879. The reversal of 81523873 is 37832518.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 46335249 + 35188624 = 6807^2 + 5932^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-81523873 is a prime.

It is a super-2 number, since 2×81523873² = 13292283737840258, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (81523879) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40761936 + 40761937.

It is an arithmetic number, because the mean of its divisors is an integer number (40761937).

Almost surely, 2^81523873 is an apocalyptic number.

It is an amenable number.

81523873 is a deficient number, since it is larger than the sum of its proper divisors (1).

81523873 is an equidigital number, since it uses as much as digits as its factorization.

81523873 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 40320, while the sum is 37.

The square root of 81523873 is about 9029.0571490051. The cubic root of 81523873 is about 433.6056520399.

The spelling of 81523873 in words is "eighty-one million, five hundred twenty-three thousand, eight hundred seventy-three".