20958181 has 2 divisors, whose sum is σ = 20958182. Its totient is φ = 20958180.

The previous prime is 20958173. The next prime is 20958211. The reversal of 20958181 is 18185902.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 20930625 + 27556 = 4575^2 + 166^2 .

It is a cyclic number.

It is not a de Polignac number, because 20958181 - 2³ = 20958173 is a prime.

It is a super-2 number, since 2×20958181² = 878490701657522, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (20958101) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10479090 + 10479091.

It is an arithmetic number, because the mean of its divisors is an integer number (10479091).

Almost surely, 2^20958181 is an apocalyptic number.

It is an amenable number.

20958181 is a deficient number, since it is larger than the sum of its proper divisors (1).

20958181 is an equidigital number, since it uses as much as digits as its factorization.

20958181 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 5760, while the sum is 34.

The square root of 20958181 is about 4578.0105941337. The cubic root of 20958181 is about 275.7091603040.

The spelling of 20958181 in words is "twenty million, nine hundred fifty-eight thousand, one hundred eighty-one".