20515503221 has 2 divisors, whose sum is σ = 20515503222. Its totient is φ = 20515503220.

The previous prime is 20515503199. The next prime is 20515503227. The reversal of 20515503221 is 12230551502.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 20274912100 + 240591121 = 142390^2 + 15511^2 .

It is a cyclic number.

It is not a de Polignac number, because 20515503221 - 2¹⁴ = 20515486837 is a prime.

It is a super-2 number, since 2×20515503221² (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 (20515503227) 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, 10257751610 + 10257751611.

It is an arithmetic number, because the mean of its divisors is an integer number (10257751611).

Almost surely, 2^20515503221 is an apocalyptic number.

It is an amenable number.

20515503221 is a deficient number, since it is larger than the sum of its proper divisors (1).

20515503221 is an equidigital number, since it uses as much as digits as its factorization.

20515503221 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 3000, while the sum is 26.

The spelling of 20515503221 in words is "twenty billion, five hundred fifteen million, five hundred three thousand, two hundred twenty-one".