21044220656 has 10 divisors (see below), whose sum is σ = 40773177552. Its totient is φ = 10522110320.

The previous prime is 21044220577. The next prime is 21044220667. The reversal of 21044220656 is 65602244012.

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, 657631880 + ... + 657631911.

Almost surely, 2^21044220656 is an apocalyptic number.

It is an amenable number.

21044220656 is a deficient number, since it is larger than the sum of its proper divisors (19728956896).

21044220656 is a wasteful number, since it uses less digits than its factorization.

21044220656 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1315263799 (or 1315263793 counting only the distinct ones).

The product of its (nonzero) digits is 23040, while the sum is 32.

Adding to 21044220656 its reverse (65602244012), we get a palindrome (86646464668).

The spelling of 21044220656 in words is "twenty-one billion, forty-four million, two hundred twenty thousand, six hundred fifty-six".