20549861 has 2 divisors, whose sum is σ = 20549862. Its totient is φ = 20549860.

The previous prime is 20549843. The next prime is 20549873. The reversal of 20549861 is 16894502.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 17724100 + 2825761 = 4210^2 + 1681^2 .

It is a cyclic number.

It is not a de Polignac number, because 20549861 - 2¹⁴ = 20533477 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (20549801) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10274930 + 10274931.

It is an arithmetic number, because the mean of its divisors is an integer number (10274931).

Almost surely, 2^20549861 is an apocalyptic number.

It is an amenable number.

20549861 is a deficient number, since it is larger than the sum of its proper divisors (1).

20549861 is an equidigital number, since it uses as much as digits as its factorization.

20549861 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 17280, while the sum is 35.

The square root of 20549861 is about 4533.1954513345. The cubic root of 20549861 is about 273.9068937924.

The spelling of 20549861 in words is "twenty million, five hundred forty-nine thousand, eight hundred sixty-one".