21000143 has 2 divisors, whose sum is σ = 21000144. Its totient is φ = 21000142.

The previous prime is 21000139. The next prime is 21000157. The reversal of 21000143 is 34100012.

It is a happy number.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21000143 - 2² = 21000139 is a prime.

21000143 is a modest number, since divided by 143 gives 21 as remainder.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21000103) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10500071 + 10500072.

It is an arithmetic number, because the mean of its divisors is an integer number (10500072).

Almost surely, 2^21000143 is an apocalyptic number.

21000143 is a deficient number, since it is larger than the sum of its proper divisors (1).

21000143 is an equidigital number, since it uses as much as digits as its factorization.

21000143 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 24, while the sum is 11.

The square root of 21000143 is about 4582.5912975084. The cubic root of 21000143 is about 275.8930438687.

Adding to 21000143 its reverse (34100012), we get a palindrome (55100155).

The spelling of 21000143 in words is "twenty-one million, one hundred forty-three", and thus it is an aban number.