21307513827581 has 2 divisors, whose sum is σ = 21307513827582. Its totient is φ = 21307513827580.

The previous prime is 21307513827557. The next prime is 21307513827637. The reversal of 21307513827581 is 18572831570312.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 19939395276025 + 1368118551556 = 4465355^2 + 1169666^2 .

It is a cyclic number.

It is not a de Polignac number, because 21307513827581 - 2³⁰ = 21306440085757 is a prime.

It is a super-2 number, since 2×21307513827581² (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 (21307513827511) 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, 10653756913790 + 10653756913791.

It is an arithmetic number, because the mean of its divisors is an integer number (10653756913791).

Almost surely, 2^{21307513827581} is an apocalyptic number.

It is an amenable number.

21307513827581 is a deficient number, since it is larger than the sum of its proper divisors (1).

21307513827581 is an equidigital number, since it uses as much as digits as its factorization.

21307513827581 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 2822400, while the sum is 53.

The spelling of 21307513827581 in words is "twenty-one trillion, three hundred seven billion, five hundred thirteen million, eight hundred twenty-seven thousand, five hundred eighty-one".