21231143 has 2 divisors, whose sum is σ = 21231144. Its totient is φ = 21231142.

The previous prime is 21231107. The next prime is 21231173. The reversal of 21231143 is 34113212.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21231143 - 2¹⁶ = 21165607 is a prime.

It is a super-2 number, since 2×21231143² = 901522866172898, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21231173) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10615571 + 10615572.

It is an arithmetic number, because the mean of its divisors is an integer number (10615572).

Almost surely, 2^21231143 is an apocalyptic number.

21231143 is a deficient number, since it is larger than the sum of its proper divisors (1).

21231143 is an equidigital number, since it uses as much as digits as its factorization.

21231143 is an evil number, because the sum of its binary digits is even.

The product of its digits is 144, while the sum is 17.

The square root of 21231143 is about 4607.7264458733. The cubic root of 21231143 is about 276.9009581317.

Adding to 21231143 its reverse (34113212), we get a palindrome (55344355).

The spelling of 21231143 in words is "twenty-one million, two hundred thirty-one thousand, one hundred forty-three".