20721108 has 12 divisors (see below), whose sum is σ = 48349280. Its totient is φ = 6907032.

The previous prime is 20721101. The next prime is 20721131. The reversal of 20721108 is 80112702.

It is a tau number, because it is divible by the number of its divisors (12).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20721101) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 863368 + ... + 863391.

Almost surely, 2^20721108 is an apocalyptic number.

It is an amenable number.

20721108 is an abundant number, since it is smaller than the sum of its proper divisors (27628172).

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

20721108 is a wasteful number, since it uses less digits than its factorization.

20721108 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1726766 (or 1726764 counting only the distinct ones).

The product of its (nonzero) digits is 224, while the sum is 21.

The square root of 20721108 is about 4552.0443758821. The cubic root of 20721108 is about 274.6656343894.

The spelling of 20721108 in words is "twenty million, seven hundred twenty-one thousand, one hundred eight".