81169786021 has 8 divisors (see below), whose sum is σ = 82493250840. Its totient is φ = 79852038912.

The previous prime is 81169786001. The next prime is 81169786051. The reversal of 81169786021 is 12068796118.

It can be written as a sum of positive squares in 4 ways, for example, as 95765796 + 81074020225 = 9786^2 + 284735^2 .

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 81169786021 - 2¹¹ = 81169783973 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81169786001) 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, 1400800 + ... + 1457593.

It is an arithmetic number, because the mean of its divisors is an integer number (10311656355).

Almost surely, 2^81169786021 is an apocalyptic number.

It is an amenable number.

81169786021 is a deficient number, since it is larger than the sum of its proper divisors (1323464819).

81169786021 is a wasteful number, since it uses less digits than its factorization.

81169786021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2858855.

The product of its (nonzero) digits is 290304, while the sum is 49.

The spelling of 81169786021 in words is "eighty-one billion, one hundred sixty-nine million, seven hundred eighty-six thousand, twenty-one".