20555367221 has 2 divisors, whose sum is σ = 20555367222. Its totient is φ = 20555367220.

The previous prime is 20555367211. The next prime is 20555367247. The reversal of 20555367221 is 12276355502.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 14667874321 + 5887492900 = 121111^2 + 76730^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-20555367221 is a prime.

It is a super-2 number, since 2×20555367221² (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 (20555367211) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10277683610 + 10277683611.

It is an arithmetic number, because the mean of its divisors is an integer number (10277683611).

Almost surely, 2^20555367221 is an apocalyptic number.

It is an amenable number.

20555367221 is a deficient number, since it is larger than the sum of its proper divisors (1).

20555367221 is an equidigital number, since it uses as much as digits as its factorization.

20555367221 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 126000, while the sum is 38.

The spelling of 20555367221 in words is "twenty billion, five hundred fifty-five million, three hundred sixty-seven thousand, two hundred twenty-one".