81643255 has 8 divisors (see below), whose sum is σ = 99352224. Its totient is φ = 64394400.

The previous prime is 81643253. The next prime is 81643279. The reversal of 81643255 is 55234618.

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

It is not a de Polignac number, because 81643255 - 2¹ = 81643253 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 81643255.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81643253) 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, 114636 + ... + 115345.

It is an arithmetic number, because the mean of its divisors is an integer number (12419028).

Almost surely, 2^81643255 is an apocalyptic number.

81643255 is a deficient number, since it is larger than the sum of its proper divisors (17708969).

81643255 is a wasteful number, since it uses less digits than its factorization.

81643255 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 230057.

The product of its digits is 28800, while the sum is 34.

The square root of 81643255 is about 9035.6657198017. The cubic root of 81643255 is about 433.8172034168.

The spelling of 81643255 in words is "eighty-one million, six hundred forty-three thousand, two hundred fifty-five".