21864143 has 12 divisors (see below), whose sum is σ = 25916760. Its totient is φ = 18384912.

The previous prime is 21864121. The next prime is 21864187. The reversal of 21864143 is 34146812.

It is not a de Polignac number, because 21864143 - 2¹⁰ = 21863119 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21864103) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 1613 + ... + 6806.

It is an arithmetic number, because the mean of its divisors is an integer number (2159730).

Almost surely, 2^21864143 is an apocalyptic number.

21864143 is a deficient number, since it is larger than the sum of its proper divisors (4052617).

21864143 is an equidigital number, since it uses as much as digits as its factorization.

21864143 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 8486 (or 8479 counting only the distinct ones).

The product of its digits is 4608, while the sum is 29.

The square root of 21864143 is about 4675.9109272953. The cubic root of 21864143 is about 279.6259588889.

The spelling of 21864143 in words is "twenty-one million, eight hundred sixty-four thousand, one hundred forty-three".