21512501109553 has 2 divisors, whose sum is σ = 21512501109554. Its totient is φ = 21512501109552.

The previous prime is 21512501109551. The next prime is 21512501109611. The reversal of 21512501109553 is 35590110521512.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 19346520747024 + 2165980362529 = 4398468^2 + 1471727^2 .

It is a cyclic number.

It is not a de Polignac number, because 21512501109553 - 2¹ = 21512501109551 is a prime.

It is a super-2 number, since 2×21512501109553² (a number of 27 digits) contains 22 as substring.

Together with 21512501109551, it forms a pair of twin primes.

It is not a weakly prime, because it can be changed into another prime (21512501109551) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10756250554776 + 10756250554777.

It is an arithmetic number, because the mean of its divisors is an integer number (10756250554777).

Almost surely, 2^{21512501109553} is an apocalyptic number.

It is an amenable number.

21512501109553 is a deficient number, since it is larger than the sum of its proper divisors (1).

21512501109553 is an equidigital number, since it uses as much as digits as its factorization.

21512501109553 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 67500, while the sum is 40.

The spelling of 21512501109553 in words is "twenty-one trillion, five hundred twelve billion, five hundred one million, one hundred nine thousand, five hundred fifty-three".