81636289 has 8 divisors (see below), whose sum is σ = 95574528. Its totient is φ = 68267040.

The previous prime is 81636283. The next prime is 81636337. The reversal of 81636289 is 98263618.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 81636289 - 2³ = 81636281 is a prime.

It is not an unprimeable number, because it can be changed into a prime (81636281) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 141937 + ... + 142510.

It is an arithmetic number, because the mean of its divisors is an integer number (11946816).

Almost surely, 2^81636289 is an apocalyptic number.

It is an amenable number.

81636289 is a deficient number, since it is larger than the sum of its proper divisors (13938239).

81636289 is a wasteful number, since it uses less digits than its factorization.

81636289 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 284495.

The product of its digits is 124416, while the sum is 43.

The square root of 81636289 is about 9035.2802391514. The cubic root of 81636289 is about 433.8048649548.

The spelling of 81636289 in words is "eighty-one million, six hundred thirty-six thousand, two hundred eighty-nine".