21055433656 has 16 divisors (see below), whose sum is σ = 39561364800. Its totient is φ = 10505736384.

The previous prime is 21055433653. The next prime is 21055433671. The reversal of 21055433656 is 65633455012.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21055433653) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2743485 + ... + 2751148.

It is an arithmetic number, because the mean of its divisors is an integer number (2472585300).

Almost surely, 2^21055433656 is an apocalyptic number.

It is an amenable number.

21055433656 is a deficient number, since it is larger than the sum of its proper divisors (18505931144).

21055433656 is a wasteful number, since it uses less digits than its factorization.

21055433656 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5495118 (or 5495114 counting only the distinct ones).

The product of its (nonzero) digits is 324000, while the sum is 40.

Adding to 21055433656 its reverse (65633455012), we get a palindrome (86688888668).

The spelling of 21055433656 in words is "twenty-one billion, fifty-five million, four hundred thirty-three thousand, six hundred fifty-six".