21365555235601 has 2 divisors, whose sum is σ = 21365555235602. Its totient is φ = 21365555235600.

The previous prime is 21365555235599. The next prime is 21365555235659. The reversal of 21365555235601 is 10653255556312.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 19798361716225 + 1567193519376 = 4449535^2 + 1251876^2 .

It is a cyclic number.

It is not a de Polignac number, because 21365555235601 - 2¹ = 21365555235599 is a prime.

Together with 21365555235599, it forms a pair of twin primes.

It is not a weakly prime, because it can be changed into another prime (21365555235001) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10682777617800 + 10682777617801.

It is an arithmetic number, because the mean of its divisors is an integer number (10682777617801).

Almost surely, 2^{21365555235601} is an apocalyptic number.

It is an amenable number.

21365555235601 is a deficient number, since it is larger than the sum of its proper divisors (1).

21365555235601 is an equidigital number, since it uses as much as digits as its factorization.

21365555235601 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 4050000, while the sum is 49.

The spelling of 21365555235601 in words is "twenty-one trillion, three hundred sixty-five billion, five hundred fifty-five million, two hundred thirty-five thousand, six hundred one".