20606889581 has 2 divisors, whose sum is σ = 20606889582. Its totient is φ = 20606889580.

The previous prime is 20606889539. The next prime is 20606889649. The reversal of 20606889581 is 18598860602.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 20589667081 + 17222500 = 143491^2 + 4150^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-20606889581 is a prime.

It is a super-2 number, since 2×20606889581² (a number of 21 digits) contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (20606889481) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10303444790 + 10303444791.

It is an arithmetic number, because the mean of its divisors is an integer number (10303444791).

Almost surely, 2^20606889581 is an apocalyptic number.

It is an amenable number.

20606889581 is a deficient number, since it is larger than the sum of its proper divisors (1).

20606889581 is an equidigital number, since it uses as much as digits as its factorization.

20606889581 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 1658880, while the sum is 53.

The spelling of 20606889581 in words is "twenty billion, six hundred six million, eight hundred eighty-nine thousand, five hundred eighty-one".