21968818958549 has 4 divisors (see below), whose sum is σ = 22246905274560. Its totient is φ = 21690732642540.

The previous prime is 21968818958521. The next prime is 21968818958621. The reversal of 21968818958549 is 94585981886912.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21968818958549 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21968818958519) 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, 139043157887 + ... + 139043158044.

It is an arithmetic number, because the mean of its divisors is an integer number (5561726318640).

Almost surely, 2^{21968818958549} is an apocalyptic number.

It is an amenable number.

21968818958549 is a deficient number, since it is larger than the sum of its proper divisors (278086316011).

21968818958549 is an equidigital number, since it uses as much as digits as its factorization.

21968818958549 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 278086316010.

The product of its digits is 3583180800, while the sum is 83.

The spelling of 21968818958549 in words is "twenty-one trillion, nine hundred sixty-eight billion, eight hundred eighteen million, nine hundred fifty-eight thousand, five hundred forty-nine".