21000211993 has 2 divisors, whose sum is σ = 21000211994. Its totient is φ = 21000211992.

The previous prime is 21000211829. The next prime is 21000212027. The reversal of 21000211993 is 39911200012.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 20736864009 + 263347984 = 144003^2 + 16228^2 .

It is a cyclic number.

It is not a de Polignac number, because 21000211993 - 2²⁹ = 20463341081 is a prime.

It is not a weakly prime, because it can be changed into another prime (21000211493) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10500105996 + 10500105997.

It is an arithmetic number, because the mean of its divisors is an integer number (10500105997).

Almost surely, 2^21000211993 is an apocalyptic number.

It is an amenable number.

21000211993 is a deficient number, since it is larger than the sum of its proper divisors (1).

21000211993 is an equidigital number, since it uses as much as digits as its factorization.

21000211993 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 972, while the sum is 28.

The spelling of 21000211993 in words is "twenty-one billion, two hundred eleven thousand, nine hundred ninety-three".