81542599 has 2 divisors, whose sum is σ = 81542600. Its totient is φ = 81542598.

The previous prime is 81542581. The next prime is 81542611. The reversal of 81542599 is 99524518.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 81542599 - 2²³ = 73153991 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (81642599) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40771299 + 40771300.

It is an arithmetic number, because the mean of its divisors is an integer number (40771300).

Almost surely, 2^81542599 is an apocalyptic number.

81542599 is a deficient number, since it is larger than the sum of its proper divisors (1).

81542599 is an equidigital number, since it uses as much as digits as its factorization.

81542599 is an evil number, because the sum of its binary digits is even.

The product of its digits is 129600, while the sum is 43.

The square root of 81542599 is about 9030.0940748145. The cubic root of 81542599 is about 433.6388491781.

The spelling of 81542599 in words is "eighty-one million, five hundred forty-two thousand, five hundred ninety-nine".