21660973543 has 4 divisors (see below), whose sum is σ = 23630152968. Its totient is φ = 19691794120.

The previous prime is 21660973513. The next prime is 21660973549. The reversal of 21660973543 is 34537906612.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21660973543 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21660973493 and 21660973502.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21660973549) 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, 984589696 + ... + 984589717.

It is an arithmetic number, because the mean of its divisors is an integer number (5907538242).

Almost surely, 2^21660973543 is an apocalyptic number.

21660973543 is a deficient number, since it is larger than the sum of its proper divisors (1969179425).

21660973543 is a wasteful number, since it uses less digits than its factorization.

21660973543 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1969179424.

The product of its (nonzero) digits is 816480, while the sum is 46.

The spelling of 21660973543 in words is "twenty-one billion, six hundred sixty million, nine hundred seventy-three thousand, five hundred forty-three".