20581221737 has 2 divisors, whose sum is σ = 20581221738. Its totient is φ = 20581221736.

The previous prime is 20581221719. The next prime is 20581221757. The reversal of 20581221737 is 73712218502.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 20581058521 + 163216 = 143461^2 + 404^2 .

It is a cyclic number.

It is not a de Polignac number, because 20581221737 - 2¹⁴ = 20581205353 is a prime.

It is a super-2 number, since 2×20581221737² (a number of 21 digits) contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 20581221737.

It is not a weakly prime, because it can be changed into another prime (20581221707) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10290610868 + 10290610869.

It is an arithmetic number, because the mean of its divisors is an integer number (10290610869).

Almost surely, 2^20581221737 is an apocalyptic number.

It is an amenable number.

20581221737 is a deficient number, since it is larger than the sum of its proper divisors (1).

20581221737 is an equidigital number, since it uses as much as digits as its factorization.

20581221737 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 47040, while the sum is 38.

The spelling of 20581221737 in words is "twenty billion, five hundred eighty-one million, two hundred twenty-one thousand, seven hundred thirty-seven".