20731231 has 2 divisors, whose sum is σ = 20731232. Its totient is φ = 20731230.

The previous prime is 20731189. The next prime is 20731241. The reversal of 20731231 is 13213702.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 20731231 - 2⁹ = 20730719 is a prime.

It is a super-2 number, since 2×20731231² = 859567877550722, which contains 22 as substring.

It is a Chen prime.

It is a junction number, because it is equal to n+sod(n) for n = 20731199 and 20731208.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (20731241) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10365615 + 10365616.

It is an arithmetic number, because the mean of its divisors is an integer number (10365616).

Almost surely, 2^20731231 is an apocalyptic number.

20731231 is a deficient number, since it is larger than the sum of its proper divisors (1).

20731231 is an equidigital number, since it uses as much as digits as its factorization.

20731231 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 252, while the sum is 19.

The square root of 20731231 is about 4553.1561580952. The cubic root of 20731231 is about 274.7103550925.

Adding to 20731231 its reverse (13213702), we get a palindrome (33944933).

The spelling of 20731231 in words is "twenty million, seven hundred thirty-one thousand, two hundred thirty-one".