21663231749 has 8 divisors (see below), whose sum is σ = 21695661720. Its totient is φ = 21630825216.

The previous prime is 21663231719. The next prime is 21663231769. The reversal of 21663231749 is 94713236612.

It can be written as a sum of positive squares in 4 ways, for example, as 15413222500 + 6250009249 = 124150^2 + 79057^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21663231749 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 (21663231719) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 2700857 + ... + 2708865.

It is an arithmetic number, because the mean of its divisors is an integer number (2711957715).

Almost surely, 2^21663231749 is an apocalyptic number.

It is an amenable number.

21663231749 is a deficient number, since it is larger than the sum of its proper divisors (32429971).

21663231749 is an equidigital number, since it uses as much as digits as its factorization.

21663231749 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 11719.

The product of its digits is 326592, while the sum is 44.

The spelling of 21663231749 in words is "twenty-one billion, six hundred sixty-three million, two hundred thirty-one thousand, seven hundred forty-nine".