21659143 has 16 divisors (see below), whose sum is σ = 25027200. Its totient is φ = 18557280.

The previous prime is 21659137. The next prime is 21659153. The reversal of 21659143 is 34195612.

It is a cyclic number.

It is not a de Polignac number, because 21659143 - 2¹⁷ = 21528071 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21659153) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 12928 + ... + 14506.

It is an arithmetic number, because the mean of its divisors is an integer number (1564200).

Almost surely, 2^21659143 is an apocalyptic number.

21659143 is a deficient number, since it is larger than the sum of its proper divisors (3368057).

21659143 is a wasteful number, since it uses less digits than its factorization.

21659143 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1662.

The product of its digits is 6480, while the sum is 31.

The square root of 21659143 is about 4653.9384396444. The cubic root of 21659143 is about 278.7492812358.

The spelling of 21659143 in words is "twenty-one million, six hundred fifty-nine thousand, one hundred forty-three".