20887549 has 2 divisors, whose sum is σ = 20887550. Its totient is φ = 20887548.

The previous prime is 20887547. The next prime is 20887567. The reversal of 20887549 is 94578802.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 19404025 + 1483524 = 4405^2 + 1218^2 .

It is a cyclic number.

It is not a de Polignac number, because 20887549 - 2¹ = 20887547 is a prime.

Together with 20887547, it forms a pair of twin primes.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (20887541) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10443774 + 10443775.

It is an arithmetic number, because the mean of its divisors is an integer number (10443775).

Almost surely, 2^20887549 is an apocalyptic number.

It is an amenable number.

20887549 is a deficient number, since it is larger than the sum of its proper divisors (1).

20887549 is an equidigital number, since it uses as much as digits as its factorization.

20887549 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 161280, while the sum is 43.

The square root of 20887549 is about 4570.2898157557. The cubic root of 20887549 is about 275.3990855725.

The spelling of 20887549 in words is "twenty million, eight hundred eighty-seven thousand, five hundred forty-nine".