81413609 has 2 divisors, whose sum is σ = 81413610. Its totient is φ = 81413608.

The previous prime is 81413593. The next prime is 81413617. The reversal of 81413609 is 90631418.

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., 70090384 + 11323225 = 8372^2 + 3365^2 .

It is a cyclic number.

It is not a de Polignac number, because 81413609 - 2⁴ = 81413593 is a prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (81413639) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40706804 + 40706805.

It is an arithmetic number, because the mean of its divisors is an integer number (40706805).

Almost surely, 2^81413609 is an apocalyptic number.

It is an amenable number.

81413609 is a deficient number, since it is larger than the sum of its proper divisors (1).

81413609 is an equidigital number, since it uses as much as digits as its factorization.

81413609 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 5184, while the sum is 32.

The square root of 81413609 is about 9022.9490190292. The cubic root of 81413609 is about 433.4100747058.

The spelling of 81413609 in words is "eighty-one million, four hundred thirteen thousand, six hundred nine".