21204593 has 4 divisors (see below), whose sum is σ = 22451940. Its totient is φ = 19957248.

The previous prime is 21204587. The next prime is 21204607. The reversal of 21204593 is 39540212.

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

It can be written as a sum of positive squares in 2 ways, for example, as 14691889 + 6512704 = 3833^2 + 2552^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21204593 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (21204553) 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, 623648 + ... + 623681.

It is an arithmetic number, because the mean of its divisors is an integer number (5612985).

Almost surely, 2^21204593 is an apocalyptic number.

It is an amenable number.

21204593 is a deficient number, since it is larger than the sum of its proper divisors (1247347).

21204593 is a wasteful number, since it uses less digits than its factorization.

21204593 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1247346.

The product of its (nonzero) digits is 2160, while the sum is 26.

The square root of 21204593 is about 4604.8445142046. The cubic root of 21204593 is about 276.7854864546.

The spelling of 21204593 in words is "twenty-one million, two hundred four thousand, five hundred ninety-three".