20721917206 has 32 divisors (see below), whose sum is σ = 32568542208. Its totient is φ = 9869571360.

The previous prime is 20721917191. The next prime is 20721917207. The reversal of 20721917206 is 60271912702.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20721917207) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 21079791 + ... + 21080773.

It is an arithmetic number, because the mean of its divisors is an integer number (1017766944).

Almost surely, 2^20721917206 is an apocalyptic number.

20721917206 is a deficient number, since it is larger than the sum of its proper divisors (11846625002).

20721917206 is a wasteful number, since it uses less digits than its factorization.

20721917206 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2436.

The product of its (nonzero) digits is 21168, while the sum is 37.

The spelling of 20721917206 in words is "twenty billion, seven hundred twenty-one million, nine hundred seventeen thousand, two hundred six".