21326164 has 6 divisors (see below), whose sum is σ = 37320794. Its totient is φ = 10663080.

The previous prime is 21326161. The next prime is 21326213. The reversal of 21326164 is 46162312.

It can be written as a sum of positive squares in only one way, i.e., 21068100 + 258064 = 4590^2 + 508^2 .

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21326161) 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 as a sum of consecutive naturals, namely, 2665767 + ... + 2665774.

Almost surely, 2^21326164 is an apocalyptic number.

It is an amenable number.

21326164 is a deficient number, since it is larger than the sum of its proper divisors (15994630).

21326164 is a wasteful number, since it uses less digits than its factorization.

21326164 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5331545 (or 5331543 counting only the distinct ones).

The product of its digits is 1728, while the sum is 25.

The square root of 21326164 is about 4618.0259852019. The cubic root of 21326164 is about 277.3134378962.

Adding to 21326164 its reverse (46162312), we get a palindrome (67488476).

The spelling of 21326164 in words is "twenty-one million, three hundred twenty-six thousand, one hundred sixty-four".