21507526502981 has 2 divisors, whose sum is σ = 21507526502982. Its totient is φ = 21507526502980.

The previous prime is 21507526502963. The next prime is 21507526503019. The reversal of 21507526502981 is 18920562570512.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 21354149313025 + 153377189956 = 4621055^2 + 391634^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21507526502981 is a prime.

It is a super-2 number, since 2×21507526502981² (a number of 27 digits) contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21507526507981) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10753763251490 + 10753763251491.

It is an arithmetic number, because the mean of its divisors is an integer number (10753763251491).

Almost surely, 2^{21507526502981} is an apocalyptic number.

It is an amenable number.

21507526502981 is a deficient number, since it is larger than the sum of its proper divisors (1).

21507526502981 is an equidigital number, since it uses as much as digits as its factorization.

21507526502981 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 3024000, while the sum is 53.

The spelling of 21507526502981 in words is "twenty-one trillion, five hundred seven billion, five hundred twenty-six million, five hundred two thousand, nine hundred eighty-one".