21539893 has 8 divisors (see below), whose sum is σ = 21990656. Its totient is φ = 21092400.

The previous prime is 21539879. The next prime is 21539899. The reversal of 21539893 is 39893512.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 21539893 - 2²¹ = 19442741 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 (21539899) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 15880 + ... + 17182.

It is an arithmetic number, because the mean of its divisors is an integer number (2748832).

Almost surely, 2^21539893 is an apocalyptic number.

It is an amenable number.

21539893 is a deficient number, since it is larger than the sum of its proper divisors (450763).

21539893 is a wasteful number, since it uses less digits than its factorization.

21539893 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1635.

The product of its digits is 58320, while the sum is 40.

The square root of 21539893 is about 4641.1090269460. The cubic root of 21539893 is about 278.2367641210.

The spelling of 21539893 in words is "twenty-one million, five hundred thirty-nine thousand, eight hundred ninety-three".