21573642361 has 2 divisors, whose sum is σ = 21573642362. Its totient is φ = 21573642360.

The previous prime is 21573642317. The next prime is 21573642367. The reversal of 21573642361 is 16324637512.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 10819952361 + 10753690000 = 104019^2 + 103700^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21573642361 is a prime.

It is not a weakly prime, because it can be changed into another prime (21573642367) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10786821180 + 10786821181.

It is an arithmetic number, because the mean of its divisors is an integer number (10786821181).

Almost surely, 2^21573642361 is an apocalyptic number.

It is an amenable number.

21573642361 is a deficient number, since it is larger than the sum of its proper divisors (1).

21573642361 is an equidigital number, since it uses as much as digits as its factorization.

21573642361 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 181440, while the sum is 40.

The spelling of 21573642361 in words is "twenty-one billion, five hundred seventy-three million, six hundred forty-two thousand, three hundred sixty-one".