21815541719 has 2 divisors, whose sum is σ = 21815541720. Its totient is φ = 21815541718.

The previous prime is 21815541689. The next prime is 21815541749. The reversal of 21815541719 is 91714551812.

It is a balanced prime because it is at equal distance from previous prime (21815541689) and next prime (21815541749).

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21815541719 is a prime.

It is a super-2 number, since 2×21815541719² (a number of 21 digits) contains 22 as substring.

It is a Sophie Germain prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21815541719.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21815541749) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10907770859 + 10907770860.

It is an arithmetic number, because the mean of its divisors is an integer number (10907770860).

Almost surely, 2^21815541719 is an apocalyptic number.

21815541719 is a deficient number, since it is larger than the sum of its proper divisors (1).

21815541719 is an equidigital number, since it uses as much as digits as its factorization.

21815541719 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 100800, while the sum is 44.

The spelling of 21815541719 in words is "twenty-one billion, eight hundred fifteen million, five hundred forty-one thousand, seven hundred nineteen".