20545181 has 2 divisors, whose sum is σ = 20545182. Its totient is φ = 20545180.

The previous prime is 20545169. The next prime is 20545183. The reversal of 20545181 is 18154502.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 13032100 + 7513081 = 3610^2 + 2741^2 .

It is a cyclic number.

It is not a de Polignac number, because 20545181 - 2¹⁸ = 20283037 is a prime.

It is a super-2 number, since 2×20545181² = 844208924645522, which contains 22 as substring.

Together with 20545183, it forms a pair of twin primes.

It is a Chen prime.

It is a self number, because there is not a number n which added to its sum of digits gives 20545181.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (20545183) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10272590 + 10272591.

It is an arithmetic number, because the mean of its divisors is an integer number (10272591).

Almost surely, 2^20545181 is an apocalyptic number.

It is an amenable number.

20545181 is a deficient number, since it is larger than the sum of its proper divisors (1).

20545181 is an equidigital number, since it uses as much as digits as its factorization.

20545181 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 1600, while the sum is 26.

The square root of 20545181 is about 4532.6792297713. The cubic root of 20545181 is about 273.8860991410.

Adding to 20545181 its reverse (18154502), we get a palindrome (38699683).

The spelling of 20545181 in words is "twenty million, five hundred forty-five thousand, one hundred eighty-one".