21321766656 has 108 divisors (see below), whose sum is σ = 65092259232. Its totient is φ = 6689169408.

The previous prime is 21321766643. The next prime is 21321766681. The reversal of 21321766656 is 65666712312.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 233016 + ... + 311351.

It is an arithmetic number, because the mean of its divisors is an integer number (602706104).

Almost surely, 2^21321766656 is an apocalyptic number.

It is an amenable number.

21321766656 is an abundant number, since it is smaller than the sum of its proper divisors (43770492576).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21321766656 is a wasteful number, since it uses less digits than its factorization.

21321766656 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 544406 (or 544389 counting only the distinct ones).

The product of its digits is 544320, while the sum is 45.

The spelling of 21321766656 in words is "twenty-one billion, three hundred twenty-one million, seven hundred sixty-six thousand, six hundred fifty-six".