21943983541 has 2 divisors, whose sum is σ = 21943983542. Its totient is φ = 21943983540.

The previous prime is 21943983499. The next prime is 21943983577. The reversal of 21943983541 is 14538934912.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 16723921041 + 5220062500 = 129321^2 + 72250^2 .

It is a cyclic number.

It is not a de Polignac number, because 21943983541 - 2⁹ = 21943983029 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21943986541) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10971991770 + 10971991771.

It is an arithmetic number, because the mean of its divisors is an integer number (10971991771).

Almost surely, 2^21943983541 is an apocalyptic number.

It is an amenable number.

21943983541 is a deficient number, since it is larger than the sum of its proper divisors (1).

21943983541 is an equidigital number, since it uses as much as digits as its factorization.

21943983541 is an evil number, because the sum of its binary digits is even.

The product of its digits is 933120, while the sum is 49.

The spelling of 21943983541 in words is "twenty-one billion, nine hundred forty-three million, nine hundred eighty-three thousand, five hundred forty-one".