21318764 has 12 divisors (see below), whose sum is σ = 37403688. Its totient is φ = 10632000.

The previous prime is 21318763. The next prime is 21318767. The reversal of 21318764 is 46781312.

It is a self number, because there is not a number n which added to its sum of digits gives 21318764.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21318761) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 5042 + ... + 8249.

It is an arithmetic number, because the mean of its divisors is an integer number (3116974).

Almost surely, 2^21318764 is an apocalyptic number.

It is an amenable number.

21318764 is a deficient number, since it is larger than the sum of its proper divisors (16084924).

21318764 is a wasteful number, since it uses less digits than its factorization.

21318764 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 13696 (or 13694 counting only the distinct ones).

The product of its digits is 8064, while the sum is 32.

The square root of 21318764 is about 4617.2247075489. The cubic root of 21318764 is about 277.2813590400.

The spelling of 21318764 in words is "twenty-one million, three hundred eighteen thousand, seven hundred sixty-four".