20431509 has 16 divisors (see below), whose sum is σ = 31337088. Its totient is φ = 11598912.

The previous prime is 20431451. The next prime is 20431547. The reversal of 20431509 is 90513402.

It is not a de Polignac number, because 20431509 - 2⁷ = 20431381 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20431549) 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 15 ways as a sum of consecutive naturals, for example, 199 + ... + 6395.

It is an arithmetic number, because the mean of its divisors is an integer number (1958568).

Almost surely, 2^20431509 is an apocalyptic number.

It is an amenable number.

20431509 is a deficient number, since it is larger than the sum of its proper divisors (10905579).

20431509 is a wasteful number, since it uses less digits than its factorization.

20431509 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6364.

The product of its (nonzero) digits is 1080, while the sum is 24.

The square root of 20431509 is about 4520.1226753264. The cubic root of 20431509 is about 273.3800473731.

It can be divided in two parts, 204 and 31509, that added together give a palindrome (31713).

The spelling of 20431509 in words is "twenty million, four hundred thirty-one thousand, five hundred nine".