21189764 has 6 divisors (see below), whose sum is σ = 37082094. Its totient is φ = 10594880.

The previous prime is 21189713. The next prime is 21189767. The reversal of 21189764 is 46798112.

It can be written as a sum of positive squares in only one way, i.e., 20070400 + 1119364 = 4480^2 + 1058^2 .

It is not an unprimeable number, because it can be changed into a prime (21189767) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 2648717 + ... + 2648724.

It is an arithmetic number, because the mean of its divisors is an integer number (6180349).

Almost surely, 2^21189764 is an apocalyptic number.

It is an amenable number.

21189764 is a deficient number, since it is larger than the sum of its proper divisors (15892330).

21189764 is a wasteful number, since it uses less digits than its factorization.

21189764 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5297445 (or 5297443 counting only the distinct ones).

The product of its digits is 24192, while the sum is 38.

The square root of 21189764 is about 4603.2340805134. The cubic root of 21189764 is about 276.7209499783.

The spelling of 21189764 in words is "twenty-one million, one hundred eighty-nine thousand, seven hundred sixty-four".