81643346405 has 16 divisors (see below), whose sum is σ = 98221339584. Its totient is φ = 65148673920.

The previous prime is 81643346381. The next prime is 81643346417. The reversal of 81643346405 is 50464334618.

It is not a de Polignac number, because 81643346405 - 2¹² = 81643342309 is a prime.

It is a Duffinian number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 3259409 + ... + 3284361.

It is an arithmetic number, because the mean of its divisors is an integer number (6138833724).

Almost surely, 2^81643346405 is an apocalyptic number.

It is an amenable number.

81643346405 is a deficient number, since it is larger than the sum of its proper divisors (16577993179).

81643346405 is a wasteful number, since it uses less digits than its factorization.

81643346405 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 26596.

The product of its (nonzero) digits is 829440, while the sum is 44.

The spelling of 81643346405 in words is "eighty-one billion, six hundred forty-three million, three hundred forty-six thousand, four hundred five".