21236981287601 has 2 divisors, whose sum is σ = 21236981287602. Its totient is φ = 21236981287600.

The previous prime is 21236981287589. The next prime is 21236981287609. The reversal of 21236981287601 is 10678218963212.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 16498414206976 + 4738567080625 = 4061824^2 + 2176825^2 .

It is a cyclic number.

It is not a de Polignac number, because 21236981287601 - 2¹⁴ = 21236981271217 is a prime.

It is a Sophie Germain prime.

It is a Curzon number.

It is not a weakly prime, because it can be changed into another prime (21236981287609) 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, 10618490643800 + 10618490643801.

It is an arithmetic number, because the mean of its divisors is an integer number (10618490643801).

Almost surely, 2^{21236981287601} is an apocalyptic number.

It is an amenable number.

21236981287601 is a deficient number, since it is larger than the sum of its proper divisors (1).

21236981287601 is an equidigital number, since it uses as much as digits as its factorization.

21236981287601 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 3483648, while the sum is 56.

The spelling of 21236981287601 in words is "twenty-one trillion, two hundred thirty-six billion, nine hundred eighty-one million, two hundred eighty-seven thousand, six hundred one".