21023205245 has 12 divisors (see below), whose sum is σ = 29346678684. Its totient is φ = 14415912000.

The previous prime is 21023205199. The next prime is 21023205251. The reversal of 21023205245 is 54250232012.

It can be written as a sum of positive squares in 2 ways, for example, as 8832616324 + 12190588921 = 93982^2 + 110411^2 .

It is not a de Polignac number, because 21023205245 - 2³⁴ = 3843336061 is a prime.

It is a Duffinian number.

It is a congruent number.

It is an unprimeable number.

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 in 11 ways as a sum of consecutive naturals, for example, 42904256 + ... + 42904745.

It is an arithmetic number, because the mean of its divisors is an integer number (2445556557).

Almost surely, 2^21023205245 is an apocalyptic number.

It is an amenable number.

21023205245 is a deficient number, since it is larger than the sum of its proper divisors (8323473439).

21023205245 is an equidigital number, since it uses as much as digits as its factorization.

21023205245 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 85809020 (or 85809013 counting only the distinct ones).

The product of its (nonzero) digits is 4800, while the sum is 26.

Adding to 21023205245 its reverse (54250232012), we get a palindrome (75273437257).

The spelling of 21023205245 in words is "twenty-one billion, twenty-three million, two hundred five thousand, two hundred forty-five".