21018075773 has 2 divisors, whose sum is σ = 21018075774. Its totient is φ = 21018075772.

The previous prime is 21018075769. The next prime is 21018075791. The reversal of 21018075773 is 37757081012.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 20989634884 + 28440889 = 144878^2 + 5333^2 .

It is a cyclic number.

It is not a de Polignac number, because 21018075773 - 2² = 21018075769 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21018075773.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21018075703) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10509037886 + 10509037887.

It is an arithmetic number, because the mean of its divisors is an integer number (10509037887).

Almost surely, 2^21018075773 is an apocalyptic number.

It is an amenable number.

21018075773 is a deficient number, since it is larger than the sum of its proper divisors (1).

21018075773 is an equidigital number, since it uses as much as digits as its factorization.

21018075773 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 82320, while the sum is 41.

The spelling of 21018075773 in words is "twenty-one billion, eighteen million, seventy-five thousand, seven hundred seventy-three".