21518143 has 2 divisors, whose sum is σ = 21518144. Its totient is φ = 21518142.

The previous prime is 21518131. The next prime is 21518197. The reversal of 21518143 is 34181512.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21518143 - 2⁵ = 21518111 is a prime.

It is a plaindrome in base 11.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21512143) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10759071 + 10759072.

It is an arithmetic number, because the mean of its divisors is an integer number (10759072).

Almost surely, 2^21518143 is an apocalyptic number.

21518143 is a deficient number, since it is larger than the sum of its proper divisors (1).

21518143 is an equidigital number, since it uses as much as digits as its factorization.

21518143 is an evil number, because the sum of its binary digits is even.

The product of its digits is 960, while the sum is 25.

The square root of 21518143 is about 4638.7652451919. The cubic root of 21518143 is about 278.1430823239.

Adding to 21518143 its reverse (34181512), we get a palindrome (55699655).

The spelling of 21518143 in words is "twenty-one million, five hundred eighteen thousand, one hundred forty-three".