21943989841 has 2 divisors, whose sum is σ = 21943989842. Its totient is φ = 21943989840.

The previous prime is 21943989833. The next prime is 21943989869. The reversal of 21943989841 is 14898934912.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 11512431616 + 10431558225 = 107296^2 + 102135^2 .

It is a cyclic number.

It is not a de Polignac number, because 21943989841 - 2³ = 21943989833 is a prime.

It is a super-2 number, since 2×21943989841² (a number of 21 digits) contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (21943989811) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10971994920 + 10971994921.

It is an arithmetic number, because the mean of its divisors is an integer number (10971994921).

Almost surely, 2^21943989841 is an apocalyptic number.

It is an amenable number.

21943989841 is a deficient number, since it is larger than the sum of its proper divisors (1).

21943989841 is an equidigital number, since it uses as much as digits as its factorization.

21943989841 is an evil number, because the sum of its binary digits is even.

The product of its digits is 4478976, while the sum is 58.

The spelling of 21943989841 in words is "twenty-one billion, nine hundred forty-three million, nine hundred eighty-nine thousand, eight hundred forty-one".