20215445521 has 2 divisors, whose sum is σ = 20215445522. Its totient is φ = 20215445520.

The previous prime is 20215445491. The next prime is 20215445581. The reversal of 20215445521 is 12554451202.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 20067555600 + 147889921 = 141660^2 + 12161^2 .

It is a cyclic number.

It is not a de Polignac number, because 20215445521 - 2⁹ = 20215445009 is a prime.

It is a super-2 number, since 2×20215445521² (a number of 21 digits) contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (20215445581) 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, 10107722760 + 10107722761.

It is an arithmetic number, because the mean of its divisors is an integer number (10107722761).

Almost surely, 2^20215445521 is an apocalyptic number.

It is an amenable number.

20215445521 is a deficient number, since it is larger than the sum of its proper divisors (1).

20215445521 is an equidigital number, since it uses as much as digits as its factorization.

20215445521 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 16000, while the sum is 31.

Adding to 20215445521 its reverse (12554451202), we get a palindrome (32769896723).

The spelling of 20215445521 in words is "twenty billion, two hundred fifteen million, four hundred forty-five thousand, five hundred twenty-one".