20581901 has 2 divisors, whose sum is σ = 20581902. Its totient is φ = 20581900.

The previous prime is 20581871. The next prime is 20581903. The reversal of 20581901 is 10918502.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 20475625 + 106276 = 4525^2 + 326^2 .

It is a cyclic number.

It is not a de Polignac number, because 20581901 - 2¹⁸ = 20319757 is a prime.

It is a super-2 number, since 2×20581901² = 847229297547602, which contains 22 as substring.

It is a Sophie Germain prime.

Together with 20581903, it forms a pair of twin primes.

It is a Chen prime.

It is a Curzon number.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (20581903) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10290950 + 10290951.

It is an arithmetic number, because the mean of its divisors is an integer number (10290951).

Almost surely, 2^20581901 is an apocalyptic number.

It is an amenable number.

20581901 is a deficient number, since it is larger than the sum of its proper divisors (1).

20581901 is an equidigital number, since it uses as much as digits as its factorization.

20581901 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 720, while the sum is 26.

The square root of 20581901 is about 4536.7280059532. The cubic root of 20581901 is about 274.0491724490.

The spelling of 20581901 in words is "twenty million, five hundred eighty-one thousand, nine hundred one".