21122213891 has 2 divisors, whose sum is σ = 21122213892. Its totient is φ = 21122213890.

The previous prime is 21122213821. The next prime is 21122213953. The reversal of 21122213891 is 19831222112.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21122213891 - 2¹⁴ = 21122197507 is a prime.

It is a super-2 number, since 2×21122213891² (a number of 21 digits) contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (21122213821) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10561106945 + 10561106946.

It is an arithmetic number, because the mean of its divisors is an integer number (10561106946).

Almost surely, 2^21122213891 is an apocalyptic number.

21122213891 is a deficient number, since it is larger than the sum of its proper divisors (1).

21122213891 is an equidigital number, since it uses as much as digits as its factorization.

21122213891 is an evil number, because the sum of its binary digits is even.

The product of its digits is 3456, while the sum is 32.

It can be divided in two parts, 2112221 and 3891, that added together give a palindrome (2116112).

The spelling of 21122213891 in words is "twenty-one billion, one hundred twenty-two million, two hundred thirteen thousand, eight hundred ninety-one".