21393593 has 4 divisors (see below), whose sum is σ = 23039268. Its totient is φ = 19747920.

The previous prime is 21393583. The next prime is 21393623. The reversal of 21393593 is 39539312.

It is a happy number.

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 11888704 + 9504889 = 3448^2 + 3083^2 .

It is a cyclic number.

It is not a de Polignac number, because 21393593 - 2¹⁶ = 21328057 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21393583) 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, 822818 + ... + 822843.

It is an arithmetic number, because the mean of its divisors is an integer number (5759817).

Almost surely, 2^21393593 is an apocalyptic number.

It is an amenable number.

21393593 is a deficient number, since it is larger than the sum of its proper divisors (1645675).

21393593 is a wasteful number, since it uses less digits than its factorization.

21393593 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1645674.

The product of its digits is 21870, while the sum is 35.

The square root of 21393593 is about 4625.3208537354. The cubic root of 21393593 is about 277.6053999966.

The spelling of 21393593 in words is "twenty-one million, three hundred ninety-three thousand, five hundred ninety-three".