20408131 has 6 divisors (see below), whose sum is σ = 20570996. Its totient is φ = 20246100.

The previous prime is 20408117. The next prime is 20408189. The reversal of 20408131 is 13180402.

It is a de Polignac number, because none of the positive numbers 2^k-20408131 is a prime.

It is a super-2 number, since 2×20408131² = 832983621826322, which contains 22 as substring.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 20408099 and 20408108.

It is not an unprimeable number, because it can be changed into a prime (20408191) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 65466 + ... + 65776.

Almost surely, 2^20408131 is an apocalyptic number.

20408131 is a deficient number, since it is larger than the sum of its proper divisors (162865).

20408131 is an frugal number, since it uses more digits than its factorization.

20408131 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 833 (or 522 counting only the distinct ones).

The product of its (nonzero) digits is 192, while the sum is 19.

The square root of 20408131 is about 4517.5359434099. The cubic root of 20408131 is about 273.2757392367.

Adding to 20408131 its reverse (13180402), we get a palindrome (33588533).

The spelling of 20408131 in words is "twenty million, four hundred eight thousand, one hundred thirty-one".