20508431 has 2 divisors, whose sum is σ = 20508432. Its totient is φ = 20508430.

The previous prime is 20508413. The next prime is 20508451. The reversal of 20508431 is 13480502.

Together with previous prime (20508413) it forms an Ormiston pair, because they use the same digits, order apart.

It is a weak prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-20508431 is a prime.

It is a super-4 number, since 4×20508431⁴ (a number of 30 digits) contains 4444 as substring. Note that it is a super-d number also for d = 2.

It is a Sophie Germain prime.

It is a junction number, because it is equal to n+sod(n) for n = 20508397 and 20508406.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (20508451) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10254215 + 10254216.

It is an arithmetic number, because the mean of its divisors is an integer number (10254216).

Almost surely, 2^20508431 is an apocalyptic number.

20508431 is a deficient number, since it is larger than the sum of its proper divisors (1).

20508431 is an equidigital number, since it uses as much as digits as its factorization.

20508431 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 960, while the sum is 23.

The square root of 20508431 is about 4528.6235215571. The cubic root of 20508431 is about 273.7226979437.

Adding to 20508431 its reverse (13480502), we get a palindrome (33988933).

The spelling of 20508431 in words is "twenty million, five hundred eight thousand, four hundred thirty-one".