81636587 has 2 divisors, whose sum is σ = 81636588. Its totient is φ = 81636586.

The previous prime is 81636563. The next prime is 81636593. The reversal of 81636587 is 78563618.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 81636587 - 2²² = 77442283 is a prime.

It is an alternating number because its digits alternate between even and odd.

It is not a weakly prime, because it can be changed into another prime (81636517) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40818293 + 40818294.

It is an arithmetic number, because the mean of its divisors is an integer number (40818294).

Almost surely, 2^81636587 is an apocalyptic number.

81636587 is a deficient number, since it is larger than the sum of its proper divisors (1).

81636587 is an equidigital number, since it uses as much as digits as its factorization.

81636587 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 241920, while the sum is 44.

The square root of 81636587 is about 9035.2967300471. The cubic root of 81636587 is about 433.8053927989.

The spelling of 81636587 in words is "eighty-one million, six hundred thirty-six thousand, five hundred eighty-seven".