20319581 has 2 divisors, whose sum is σ = 20319582. Its totient is φ = 20319580.

The previous prime is 20319503. The next prime is 20319583. The reversal of 20319581 is 18591302.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 16080100 + 4239481 = 4010^2 + 2059^2 .

It is a cyclic number.

It is not a de Polignac number, because 20319581 - 2¹⁴ = 20303197 is a prime.

It is a super-2 number, since 2×20319581² = 825770744031122, which contains 22 as substring.

Together with 20319583, it forms a pair of twin primes.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (20319583) 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, 10159790 + 10159791.

It is an arithmetic number, because the mean of its divisors is an integer number (10159791).

Almost surely, 2^20319581 is an apocalyptic number.

It is an amenable number.

20319581 is a deficient number, since it is larger than the sum of its proper divisors (1).

20319581 is an equidigital number, since it uses as much as digits as its factorization.

20319581 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 2160, while the sum is 29.

The square root of 20319581 is about 4507.7245922971. The cubic root of 20319581 is about 272.8799223249.

The spelling of 20319581 in words is "twenty million, three hundred nineteen thousand, five hundred eighty-one".