21206764 has 6 divisors (see below), whose sum is σ = 37111844. Its totient is φ = 10603380.

The previous prime is 21206753. The next prime is 21206791. The reversal of 21206764 is 46760212.

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, 2650842 + ... + 2650849.

Almost surely, 2^21206764 is an apocalyptic number.

It is an amenable number.

21206764 is a deficient number, since it is larger than the sum of its proper divisors (15905080).

21206764 is a wasteful number, since it uses less digits than its factorization.

21206764 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5301695 (or 5301693 counting only the distinct ones).

The product of its (nonzero) digits is 4032, while the sum is 28.

The square root of 21206764 is about 4605.0802381718. The cubic root of 21206764 is about 276.7949322192.

Adding to 21206764 its reverse (46760212), we get a palindrome (67966976).

The spelling of 21206764 in words is "twenty-one million, two hundred six thousand, seven hundred sixty-four".