21143911 has 2 divisors, whose sum is σ = 21143912. Its totient is φ = 21143910.

The previous prime is 21143897. The next prime is 21143921. The reversal of 21143911 is 11934112.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21143911 - 2⁵ = 21143879 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21143921) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10571955 + 10571956.

It is an arithmetic number, because the mean of its divisors is an integer number (10571956).

Almost surely, 2^21143911 is an apocalyptic number.

21143911 is a deficient number, since it is larger than the sum of its proper divisors (1).

21143911 is an equidigital number, since it uses as much as digits as its factorization.

21143911 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 216, while the sum is 22.

The square root of 21143911 is about 4598.2508631000. The cubic root of 21143911 is about 276.5212049656.

It can be divided in two parts, 2 and 1143911, that multiplied together give a palindrome (2287822).

The spelling of 21143911 in words is "twenty-one million, one hundred forty-three thousand, nine hundred eleven".