21036253793 has 2 divisors, whose sum is σ = 21036253794. Its totient is φ = 21036253792.

The previous prime is 21036253757. The next prime is 21036253817. The reversal of 21036253793 is 39735263012.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 17316717649 + 3719536144 = 131593^2 + 60988^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21036253793 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21036253793.

It is not a weakly prime, because it can be changed into another prime (21036253723) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10518126896 + 10518126897.

It is an arithmetic number, because the mean of its divisors is an integer number (10518126897).

Almost surely, 2^21036253793 is an apocalyptic number.

It is an amenable number.

21036253793 is a deficient number, since it is larger than the sum of its proper divisors (1).

21036253793 is an equidigital number, since it uses as much as digits as its factorization.

21036253793 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 204120, while the sum is 41.

The spelling of 21036253793 in words is "twenty-one billion, thirty-six million, two hundred fifty-three thousand, seven hundred ninety-three".