20988109 has 2 divisors, whose sum is σ = 20988110. Its totient is φ = 20988108.

The previous prime is 20988101. The next prime is 20988119. The reversal of 20988109 is 90188902.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 18966025 + 2022084 = 4355^2 + 1422^2 .

It is a cyclic number.

It is not a de Polignac number, because 20988109 - 2³ = 20988101 is a prime.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (20988101) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10494054 + 10494055.

It is an arithmetic number, because the mean of its divisors is an integer number (10494055).

Almost surely, 2^20988109 is an apocalyptic number.

It is an amenable number.

20988109 is a deficient number, since it is larger than the sum of its proper divisors (1).

20988109 is an equidigital number, since it uses as much as digits as its factorization.

20988109 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 10368, while the sum is 37.

The square root of 20988109 is about 4581.2780967761. The cubic root of 20988109 is about 275.8403342073.

The spelling of 20988109 in words is "twenty million, nine hundred eighty-eight thousand, one hundred nine".