20938509 has 24 divisors (see below), whose sum is σ = 32348160. Its totient is φ = 13004928.

The previous prime is 20938507. The next prime is 20938529. The reversal of 20938509 is 90583902.

20938509 = T₁₅₆₁ + T₁₅₆₂ + ... + T₁₅₇₇.

It is not a de Polignac number, because 20938509 - 2¹ = 20938507 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20938501) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 15732 + ... + 17010.

It is an arithmetic number, because the mean of its divisors is an integer number (1347840).

Almost surely, 2^20938509 is an apocalyptic number.

It is an amenable number.

20938509 is a deficient number, since it is larger than the sum of its proper divisors (11409651).

20938509 is a wasteful number, since it uses less digits than its factorization.

20938509 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1409 (or 1406 counting only the distinct ones).

The product of its (nonzero) digits is 19440, while the sum is 36.

The square root of 20938509 is about 4575.8615582205. The cubic root of 20938509 is about 275.6228702382.

The spelling of 20938509 in words is "twenty million, nine hundred thirty-eight thousand, five hundred nine".