21721272763 has 4 divisors (see below), whose sum is σ = 21721577760. Its totient is φ = 21720967768.

The previous prime is 21721272751. The next prime is 21721272791. The reversal of 21721272763 is 36727212712.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It is a cyclic number.

It is not a de Polignac number, because 21721272763 - 2¹³ = 21721264571 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21721272163) 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 3 ways as a sum of consecutive naturals, for example, 17493 + ... + 209161.

It is an arithmetic number, because the mean of its divisors is an integer number (5430394440).

Almost surely, 2^21721272763 is an apocalyptic number.

21721272763 is a deficient number, since it is larger than the sum of its proper divisors (304997).

21721272763 is a wasteful number, since it uses less digits than its factorization.

21721272763 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 304996.

The product of its digits is 98784, while the sum is 40.

The spelling of 21721272763 in words is "twenty-one billion, seven hundred twenty-one million, two hundred seventy-two thousand, seven hundred sixty-three".