20531431 has 2 divisors, whose sum is σ = 20531432. Its totient is φ = 20531430.

The previous prime is 20531429. The next prime is 20531437. The reversal of 20531431 is 13413502.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 20531431 - 2¹ = 20531429 is a prime.

It is a super-2 number, since 2×20531431² = 843079317815522, which contains 22 as substring.

Together with 20531429, it forms a pair of twin primes.

It is a junction number, because it is equal to n+sod(n) for n = 20531399 and 20531408.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (20531437) 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 as a sum of consecutive naturals, namely, 10265715 + 10265716.

It is an arithmetic number, because the mean of its divisors is an integer number (10265716).

Almost surely, 2^20531431 is an apocalyptic number.

20531431 is a deficient number, since it is larger than the sum of its proper divisors (1).

20531431 is an equidigital number, since it uses as much as digits as its factorization.

20531431 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 360, while the sum is 19.

The square root of 20531431 is about 4531.1622129427. The cubic root of 20531431 is about 273.8249854700.

Adding to 20531431 its reverse (13413502), we get a palindrome (33944933).

The spelling of 20531431 in words is "twenty million, five hundred thirty-one thousand, four hundred thirty-one".