20581616641 has 2 divisors, whose sum is σ = 20581616642. Its totient is φ = 20581616640.

The previous prime is 20581616597. The next prime is 20581616687. The reversal of 20581616641 is 14661618502.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 11865527041 + 8716089600 = 108929^2 + 93360^2 .

It is a cyclic number.

It is not a de Polignac number, because 20581616641 - 2⁷ = 20581616513 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 20581616594 and 20581616603.

It is not a weakly prime, because it can be changed into another prime (20581616141) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10290808320 + 10290808321.

It is an arithmetic number, because the mean of its divisors is an integer number (10290808321).

Almost surely, 2^20581616641 is an apocalyptic number.

It is an amenable number.

20581616641 is a deficient number, since it is larger than the sum of its proper divisors (1).

20581616641 is an equidigital number, since it uses as much as digits as its factorization.

20581616641 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 69120, while the sum is 40.

The spelling of 20581616641 in words is "twenty billion, five hundred eighty-one million, six hundred sixteen thousand, six hundred forty-one".