21305893 has 16 divisors (see below), whose sum is σ = 24938496. Its totient is φ = 17826480.

The previous prime is 21305891. The next prime is 21305909. The reversal of 21305893 is 39850312.

It is a happy number.

It is not a de Polignac number, because 21305893 - 2¹ = 21305891 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 (21305891) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 80880 + ... + 81142.

It is an arithmetic number, because the mean of its divisors is an integer number (1558656).

Almost surely, 2^21305893 is an apocalyptic number.

It is an amenable number.

21305893 is a deficient number, since it is larger than the sum of its proper divisors (3632603).

21305893 is a wasteful number, since it uses less digits than its factorization.

21305893 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 504.

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

The square root of 21305893 is about 4615.8306944688. The cubic root of 21305893 is about 277.2255458162.

The spelling of 21305893 in words is "twenty-one million, three hundred five thousand, eight hundred ninety-three".