21830810581 has 4 divisors (see below), whose sum is σ = 21831626700. Its totient is φ = 21829994464.

The previous prime is 21830810563. The next prime is 21830810587. The reversal of 21830810581 is 18501803812.

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 6537531025 + 15293279556 = 80855^2 + 123666^2 .

It is a cyclic number.

It is not a de Polignac number, because 21830810581 - 2⁹ = 21830810069 is a prime.

It is a super-2 number, since 2×21830810581² (a number of 21 digits) contains 22 as substring.

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 21830810581.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21830810587) 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, 366526 + ... + 421903.

It is an arithmetic number, because the mean of its divisors is an integer number (5457906675).

Almost surely, 2^21830810581 is an apocalyptic number.

It is an amenable number.

21830810581 is a deficient number, since it is larger than the sum of its proper divisors (816119).

21830810581 is an equidigital number, since it uses as much as digits as its factorization.

21830810581 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 816118.

The product of its (nonzero) digits is 15360, while the sum is 37.

The spelling of 21830810581 in words is "twenty-one billion, eight hundred thirty million, eight hundred ten thousand, five hundred eighty-one".