81643335 has 12 divisors (see below), whose sum is σ = 130685352. Its totient is φ = 43524448.

The previous prime is 81643327. The next prime is 81643337. The reversal of 81643335 is 53334618.

It is not a de Polignac number, because 81643335 - 2³ = 81643327 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 81643296 and 81643305.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81643337) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 33829 + ... + 36161.

It is an arithmetic number, because the mean of its divisors is an integer number (10890446).

Almost surely, 2^81643335 is an apocalyptic number.

81643335 is a deficient number, since it is larger than the sum of its proper divisors (49042017).

81643335 is an frugal number, since it uses more digits than its factorization.

81643335 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4674 (or 2341 counting only the distinct ones).

The product of its digits is 25920, while the sum is 33.

The square root of 81643335 is about 9035.6701467019. The cubic root of 81643335 is about 433.8173451119.

The spelling of 81643335 in words is "eighty-one million, six hundred forty-three thousand, three hundred thirty-five".