21318574 has 4 divisors (see below), whose sum is σ = 31977864. Its totient is φ = 10659286.

The previous prime is 21318541. The next prime is 21318599. The reversal of 21318574 is 47581312.

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

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 5329642 + ... + 5329645.

It is an arithmetic number, because the mean of its divisors is an integer number (7994466).

Almost surely, 2^21318574 is an apocalyptic number.

21318574 is a deficient number, since it is larger than the sum of its proper divisors (10659290).

21318574 is a wasteful number, since it uses less digits than its factorization.

21318574 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10659289.

The product of its digits is 6720, while the sum is 31.

The square root of 21318574 is about 4617.2041323728. The cubic root of 21318574 is about 277.2805352960.

Adding to 21318574 its reverse (47581312), we get a palindrome (68899886).

The spelling of 21318574 in words is "twenty-one million, three hundred eighteen thousand, five hundred seventy-four".