21318575 has 12 divisors (see below), whose sum is σ = 26699928. Its totient is φ = 16884000.

The previous prime is 21318541. The next prime is 21318599. The reversal of 21318575 is 57581312.

It is not a de Polignac number, because 21318575 - 2⁶ = 21318511 is a prime.

It is a Duffinian number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 1697 + ... + 6746.

It is an arithmetic number, because the mean of its divisors is an integer number (2224994).

Almost surely, 2^21318575 is an apocalyptic number.

21318575 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

21318575 is a deficient number, since it is larger than the sum of its proper divisors (5381353).

21318575 is a wasteful number, since it uses less digits than its factorization.

21318575 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 8554 (or 8549 counting only the distinct ones).

The product of its digits is 8400, while the sum is 32.

The square root of 21318575 is about 4617.2042406634. The cubic root of 21318575 is about 277.2805396315.

Adding to 21318575 its reverse (57581312), we get a palindrome (78899887).

The spelling of 21318575 in words is "twenty-one million, three hundred eighteen thousand, five hundred seventy-five".