21211119991 has 2 divisors, whose sum is σ = 21211119992. Its totient is φ = 21211119990.

The previous prime is 21211119971. The next prime is 21211120001. The reversal of 21211119991 is 19991111212.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21211119991 - 2¹³ = 21211111799 is a prime.

It is a super-2 number, since 2×21211119991² (a number of 21 digits) contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 21211119991.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21211119911) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10605559995 + 10605559996.

It is an arithmetic number, because the mean of its divisors is an integer number (10605559996).

Almost surely, 2^21211119991 is an apocalyptic number.

21211119991 is a deficient number, since it is larger than the sum of its proper divisors (1).

21211119991 is an equidigital number, since it uses as much as digits as its factorization.

21211119991 is an evil number, because the sum of its binary digits is even.

The product of its digits is 2916, while the sum is 37.

The spelling of 21211119991 in words is "twenty-one billion, two hundred eleven million, one hundred nineteen thousand, nine hundred ninety-one".