81845621029 has 4 divisors (see below), whose sum is σ = 81852214284. Its totient is φ = 81839027776.

The previous prime is 81845621027. The next prime is 81845621047. The reversal of 81845621029 is 92012654818.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 27322437025 + 54523184004 = 165295^2 + 233502^2 .

It is a cyclic number.

It is not a de Polignac number, because 81845621029 - 2¹ = 81845621027 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 81845621029.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81845621027) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 3277972 + ... + 3302845.

It is an arithmetic number, because the mean of its divisors is an integer number (20463053571).

Almost surely, 2^81845621029 is an apocalyptic number.

It is an amenable number.

81845621029 is a deficient number, since it is larger than the sum of its proper divisors (6593255).

81845621029 is a wasteful number, since it uses less digits than its factorization.

81845621029 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6593254.

The product of its (nonzero) digits is 276480, while the sum is 46.

The spelling of 81845621029 in words is "eighty-one billion, eight hundred forty-five million, six hundred twenty-one thousand, twenty-nine".