21122159521 has 2 divisors, whose sum is σ = 21122159522. Its totient is φ = 21122159520.

The previous prime is 21122159459. The next prime is 21122159537. The reversal of 21122159521 is 12595122112.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 18744621921 + 2377537600 = 136911^2 + 48760^2 .

It is a cyclic number.

It is not a de Polignac number, because 21122159521 - 2²⁵ = 21088605089 is a prime.

It is a super-3 number, since 3×21122159521³ (a number of 32 digits) contains 333 as substring. Note that it is a super-d number also for d = 2.

It is not a weakly prime, because it can be changed into another prime (21122159551) 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, 10561079760 + 10561079761.

It is an arithmetic number, because the mean of its divisors is an integer number (10561079761).

Almost surely, 2^21122159521 is an apocalyptic number.

It is an amenable number.

21122159521 is a deficient number, since it is larger than the sum of its proper divisors (1).

21122159521 is an equidigital number, since it uses as much as digits as its factorization.

21122159521 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 3600, while the sum is 31.

The spelling of 21122159521 in words is "twenty-one billion, one hundred twenty-two million, one hundred fifty-nine thousand, five hundred twenty-one".