21105143 has 16 divisors (see below), whose sum is σ = 23718240. Its totient is φ = 18714240.

The previous prime is 21105121. The next prime is 21105169. The reversal of 21105143 is 34150112.

It is a de Polignac number, because none of the positive numbers 2^k-21105143 is a prime.

It is a super-2 number, since 2×21105143² = 890854122100898, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (17).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21105043) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 116513 + ... + 116693.

It is an arithmetic number, because the mean of its divisors is an integer number (1482390).

Almost surely, 2^21105143 is an apocalyptic number.

21105143 is a deficient number, since it is larger than the sum of its proper divisors (2613097).

21105143 is an equidigital number, since it uses as much as digits as its factorization.

21105143 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 255 (or 217 counting only the distinct ones).

The product of its (nonzero) digits is 120, while the sum is 17.

The square root of 21105143 is about 4594.0334130261. The cubic root of 21105143 is about 276.3520982399.

Adding to 21105143 its reverse (34150112), we get a palindrome (55255255).

The spelling of 21105143 in words is "twenty-one million, one hundred five thousand, one hundred forty-three".