21000198959 has 2 divisors, whose sum is σ = 21000198960. Its totient is φ = 21000198958.

The previous prime is 21000198949. The next prime is 21000198979. The reversal of 21000198959 is 95989100012.

It is a happy number.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21000198959 - 2¹⁶ = 21000133423 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21000198949) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10500099479 + 10500099480.

It is an arithmetic number, because the mean of its divisors is an integer number (10500099480).

Almost surely, 2^21000198959 is an apocalyptic number.

21000198959 is a deficient number, since it is larger than the sum of its proper divisors (1).

21000198959 is an equidigital number, since it uses as much as digits as its factorization.

21000198959 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 58320, while the sum is 44.

The spelling of 21000198959 in words is "twenty-one billion, one hundred ninety-eight thousand, nine hundred fifty-nine".