21391733773 has 2 divisors, whose sum is σ = 21391733774. Its totient is φ = 21391733772.

The previous prime is 21391733749. The next prime is 21391733791. The reversal of 21391733773 is 37733719312.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 21363622569 + 28111204 = 146163^2 + 5302^2 .

It is a cyclic number.

It is not a de Polignac number, because 21391733773 - 2¹³ = 21391725581 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21391734773) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10695866886 + 10695866887.

It is an arithmetic number, because the mean of its divisors is an integer number (10695866887).

Almost surely, 2^21391733773 is an apocalyptic number.

It is an amenable number.

21391733773 is a deficient number, since it is larger than the sum of its proper divisors (1).

21391733773 is an equidigital number, since it uses as much as digits as its factorization.

21391733773 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 500094, while the sum is 46.

The spelling of 21391733773 in words is "twenty-one billion, three hundred ninety-one million, seven hundred thirty-three thousand, seven hundred seventy-three".