20889581 has 2 divisors, whose sum is σ = 20889582. Its totient is φ = 20889580.

The previous prime is 20889563. The next prime is 20889593. The reversal of 20889581 is 18598802.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 12187081 + 8702500 = 3491^2 + 2950^2 .

It is a cyclic number.

It is not a de Polignac number, because 20889581 - 2¹⁸ = 20627437 is a prime.

It is a super-2 number, since 2×20889581² = 872749188711122, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (20889521) 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, 10444790 + 10444791.

It is an arithmetic number, because the mean of its divisors is an integer number (10444791).

Almost surely, 2^20889581 is an apocalyptic number.

It is an amenable number.

20889581 is a deficient number, since it is larger than the sum of its proper divisors (1).

20889581 is an equidigital number, since it uses as much as digits as its factorization.

20889581 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 46080, while the sum is 41.

The square root of 20889581 is about 4570.5121157262. The cubic root of 20889581 is about 275.4080158176.

The spelling of 20889581 in words is "twenty million, eight hundred eighty-nine thousand, five hundred eighty-one".