81473993 has 2 divisors, whose sum is σ = 81473994. Its totient is φ = 81473992.

The previous prime is 81473947. The next prime is 81474031. The reversal of 81473993 is 39937418.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 76510009 + 4963984 = 8747^2 + 2228^2 .

It is a cyclic number.

It is not a de Polignac number, because 81473993 - 2²² = 77279689 is a prime.

It is not a weakly prime, because it can be changed into another prime (81473933) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40736996 + 40736997.

It is an arithmetic number, because the mean of its divisors is an integer number (40736997).

Almost surely, 2^81473993 is an apocalyptic number.

It is an amenable number.

81473993 is a deficient number, since it is larger than the sum of its proper divisors (1).

81473993 is an equidigital number, since it uses as much as digits as its factorization.

81473993 is an evil number, because the sum of its binary digits is even.

The product of its digits is 163296, while the sum is 44.

The square root of 81473993 is about 9026.2945331958. The cubic root of 81473993 is about 433.5172008020.

The spelling of 81473993 in words is "eighty-one million, four hundred seventy-three thousand, nine hundred ninety-three".