81573857 has 2 divisors, whose sum is σ = 81573858. Its totient is φ = 81573856.

The previous prime is 81573841. The next prime is 81573913. The reversal of 81573857 is 75837518.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 54523456 + 27050401 = 7384^2 + 5201^2 .

It is a cyclic number.

It is not a de Polignac number, because 81573857 - 2⁴ = 81573841 is a prime.

It is a super-3 number, since 3×81573857³ (a number of 25 digits) contains 333 as substring.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (81573827) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40786928 + 40786929.

It is an arithmetic number, because the mean of its divisors is an integer number (40786929).

Almost surely, 2^81573857 is an apocalyptic number.

It is an amenable number.

81573857 is a deficient number, since it is larger than the sum of its proper divisors (1).

81573857 is an equidigital number, since it uses as much as digits as its factorization.

81573857 is an evil number, because the sum of its binary digits is even.

The product of its digits is 235200, while the sum is 44.

The square root of 81573857 is about 9031.8246772178. The cubic root of 81573857 is about 433.6942515146.

The spelling of 81573857 in words is "eighty-one million, five hundred seventy-three thousand, eight hundred fifty-seven".