20431381 has 2 divisors, whose sum is σ = 20431382. Its totient is φ = 20431380.

The previous prime is 20431343. The next prime is 20431409. The reversal of 20431381 is 18313402.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 12780625 + 7650756 = 3575^2 + 2766^2 .

It is a cyclic number.

It is not a de Polignac number, because 20431381 - 2¹¹ = 20429333 is a prime.

It is a super-2 number, since 2×20431381² = 834882659134322, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (20432381) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10215690 + 10215691.

It is an arithmetic number, because the mean of its divisors is an integer number (10215691).

Almost surely, 2^20431381 is an apocalyptic number.

It is an amenable number.

20431381 is a deficient number, since it is larger than the sum of its proper divisors (1).

20431381 is an equidigital number, since it uses as much as digits as its factorization.

20431381 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 576, while the sum is 22.

The square root of 20431381 is about 4520.1085163965. The cubic root of 20431381 is about 273.3794764785.

Adding to 20431381 its reverse (18313402), we get a palindrome (38744783).

The spelling of 20431381 in words is "twenty million, four hundred thirty-one thousand, three hundred eighty-one".