21598943 has 4 divisors (see below), whose sum is σ = 22101288. Its totient is φ = 21096600.

The previous prime is 21598921. The next prime is 21598963. The reversal of 21598943 is 34989512.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 21598943 - 2⁶ = 21598879 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 21598943.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21598963) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 251108 + ... + 251193.

It is an arithmetic number, because the mean of its divisors is an integer number (5525322).

Almost surely, 2^21598943 is an apocalyptic number.

21598943 is a deficient number, since it is larger than the sum of its proper divisors (502345).

21598943 is an equidigital number, since it uses as much as digits as its factorization.

21598943 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 502344.

The product of its digits is 77760, while the sum is 41.

The square root of 21598943 is about 4647.4662989633. The cubic root of 21598943 is about 278.4907872025.

The spelling of 21598943 in words is "twenty-one million, five hundred ninety-eight thousand, nine hundred forty-three".