21220000664 has 8 divisors (see below), whose sum is σ = 39787501260. Its totient is φ = 10610000328.

The previous prime is 21220000649. The next prime is 21220000699. The reversal of 21220000664 is 46600002212.

It is a tau number, because it is divible by the number of its divisors (8).

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 1326250034 + ... + 1326250049.

Almost surely, 2^21220000664 is an apocalyptic number.

It is an amenable number.

21220000664 is a deficient number, since it is larger than the sum of its proper divisors (18567500596).

21220000664 is a wasteful number, since it uses less digits than its factorization.

21220000664 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2652500089 (or 2652500085 counting only the distinct ones).

The product of its (nonzero) digits is 1152, while the sum is 23.

Adding to 21220000664 its reverse (46600002212), we get a palindrome (67820002876).

The spelling of 21220000664 in words is "twenty-one billion, two hundred twenty million, six hundred sixty-four", and thus it is an aban number.