81749599 has 2 divisors, whose sum is σ = 81749600. Its totient is φ = 81749598.

The previous prime is 81749587. The next prime is 81749623. The reversal of 81749599 is 99594718.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 81749599 - 2¹¹ = 81747551 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (81749099) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40874799 + 40874800.

It is an arithmetic number, because the mean of its divisors is an integer number (40874800).

Almost surely, 2^81749599 is an apocalyptic number.

81749599 is a deficient number, since it is larger than the sum of its proper divisors (1).

81749599 is an equidigital number, since it uses as much as digits as its factorization.

81749599 is an evil number, because the sum of its binary digits is even.

The product of its digits is 816480, while the sum is 52.

The square root of 81749599 is about 9041.5484846347. The cubic root of 81749599 is about 434.0054771478.

The spelling of 81749599 in words is "eighty-one million, seven hundred forty-nine thousand, five hundred ninety-nine".