20431240 has 32 divisors (see below), whose sum is σ = 46606680. Its totient is φ = 8059392.

The previous prime is 20431237. The next prime is 20431247. The reversal of 20431240 is 4213402.

It can be written as a sum of positive squares in 4 ways, for example, as 15350724 + 5080516 = 3918^2 + 2254^2 .

It is not an unprimeable number, because it can be changed into a prime (20431247) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 579 + ... + 6418.

Almost surely, 2^20431240 is an apocalyptic number.

20431240 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

20431240 is an abundant number, since it is smaller than the sum of its proper divisors (26175440).

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

20431240 is a wasteful number, since it uses less digits than its factorization.

20431240 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7081 (or 7077 counting only the distinct ones).

The product of its (nonzero) digits is 192, while the sum is 16.

The square root of 20431240 is about 4520.0929193989. The cubic root of 20431240 is about 273.3788475995.

Adding to 20431240 its reverse (4213402), we get a palindrome (24644642).

The spelling of 20431240 in words is "twenty million, four hundred thirty-one thousand, two hundred forty".