21765966243 has 8 divisors (see below), whose sum is σ = 33167186688. Its totient is φ = 12437694984.

The previous prime is 21765966239. The next prime is 21765966289. The reversal of 21765966243 is 34266956712.

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

It is not a de Polignac number, because 21765966243 - 2² = 21765966239 is a prime.

It is a Smith number, since the sum of its digits (51) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is not an unprimeable number, because it can be changed into a prime (21765967243) 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, 518237271 + ... + 518237312.

It is an arithmetic number, because the mean of its divisors is an integer number (4145898336).

Almost surely, 2^21765966243 is an apocalyptic number.

21765966243 is a deficient number, since it is larger than the sum of its proper divisors (11401220445).

21765966243 is a wasteful number, since it uses less digits than its factorization.

21765966243 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1036474593.

The product of its digits is 3265920, while the sum is 51.

The spelling of 21765966243 in words is "twenty-one billion, seven hundred sixty-five million, nine hundred sixty-six thousand, two hundred forty-three".