20909980 has 48 divisors (see below), whose sum is σ = 54048960. Its totient is φ = 6617088.

The previous prime is 20909969. The next prime is 20909981. The reversal of 20909980 is 8990902.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20909981) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 3925 + ... + 7564.

It is an arithmetic number, because the mean of its divisors is an integer number (1126020).

Almost surely, 2^20909980 is an apocalyptic number.

20909980 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

20909980 is an abundant number, since it is smaller than the sum of its proper divisors (33138980).

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

20909980 is a wasteful number, since it uses less digits than its factorization.

20909980 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 11518 (or 11516 counting only the distinct ones).

The product of its (nonzero) digits is 11664, while the sum is 37.

The square root of 20909980 is about 4572.7431591989. The cubic root of 20909980 is about 275.4976333867.

The spelling of 20909980 in words is "twenty million, nine hundred nine thousand, nine hundred eighty".