21245604773 has 2 divisors, whose sum is σ = 21245604774. Its totient is φ = 21245604772.

The previous prime is 21245604739. The next prime is 21245604791. The reversal of 21245604773 is 37740654212.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 12536609089 + 8708995684 = 111967^2 + 93322^2 .

It is a cyclic number.

It is not a de Polignac number, because 21245604773 - 2²⁰ = 21244556197 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21245604773.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21245603773) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10622802386 + 10622802387.

It is an arithmetic number, because the mean of its divisors is an integer number (10622802387).

Almost surely, 2^21245604773 is an apocalyptic number.

It is an amenable number.

21245604773 is a deficient number, since it is larger than the sum of its proper divisors (1).

21245604773 is an equidigital number, since it uses as much as digits as its factorization.

21245604773 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 282240, while the sum is 41.

The spelling of 21245604773 in words is "twenty-one billion, two hundred forty-five million, six hundred four thousand, seven hundred seventy-three".