21191143 has 2 divisors, whose sum is σ = 21191144. Its totient is φ = 21191142.

The previous prime is 21191123. The next prime is 21191147. The reversal of 21191143 is 34119112.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21191143 - 2⁵ = 21191111 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21191147) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10595571 + 10595572.

It is an arithmetic number, because the mean of its divisors is an integer number (10595572).

Almost surely, 2^21191143 is an apocalyptic number.

21191143 is a deficient number, since it is larger than the sum of its proper divisors (1).

21191143 is an equidigital number, since it uses as much as digits as its factorization.

21191143 is an evil number, because the sum of its binary digits is even.

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

The square root of 21191143 is about 4603.3838640722. The cubic root of 21191143 is about 276.7269527180.

The spelling of 21191143 in words is "twenty-one million, one hundred ninety-one thousand, one hundred forty-three".