81859511 has 2 divisors, whose sum is σ = 81859512. Its totient is φ = 81859510.

The previous prime is 81859483. The next prime is 81859529. The reversal of 81859511 is 11595818.

It is a happy number.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 81859511 - 2¹⁸ = 81597367 is a prime.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (81859111) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40929755 + 40929756.

It is an arithmetic number, because the mean of its divisors is an integer number (40929756).

Almost surely, 2^81859511 is an apocalyptic number.

81859511 is a deficient number, since it is larger than the sum of its proper divisors (1).

81859511 is an equidigital number, since it uses as much as digits as its factorization.

81859511 is an evil number, because the sum of its binary digits is even.

The product of its digits is 14400, while the sum is 38.

The square root of 81859511 is about 9047.6246053868. The cubic root of 81859511 is about 434.1998962356.

The spelling of 81859511 in words is "eighty-one million, eight hundred fifty-nine thousand, five hundred eleven".