21420143 has 2 divisors, whose sum is σ = 21420144. Its totient is φ = 21420142.

The previous prime is 21420137. The next prime is 21420169. The reversal of 21420143 is 34102412.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21420143 - 2⁶ = 21420079 is a prime.

It is a super-2 number, since 2×21420143² = 917645052280898, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21420103) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10710071 + 10710072.

It is an arithmetic number, because the mean of its divisors is an integer number (10710072).

Almost surely, 2^21420143 is an apocalyptic number.

21420143 is a deficient number, since it is larger than the sum of its proper divisors (1).

21420143 is an equidigital number, since it uses as much as digits as its factorization.

21420143 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 192, while the sum is 17.

The square root of 21420143 is about 4628.1900349921. The cubic root of 21420143 is about 277.7201910076.

Adding to 21420143 its reverse (34102412), we get a palindrome (55522555).

The spelling of 21420143 in words is "twenty-one million, four hundred twenty thousand, one hundred forty-three".