21086556245 has 4 divisors (see below), whose sum is σ = 25303867500. Its totient is φ = 16869244992.

The previous prime is 21086556223. The next prime is 21086556263. The reversal of 21086556245 is 54265568012.

It is a happy number.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 12293930884 + 8792625361 = 110878^2 + 93769^2 .

It is a cyclic number.

It is not a de Polignac number, because 21086556245 - 2⁶ = 21086556181 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 21086556196 and 21086556205.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2108655620 + ... + 2108655629.

It is an arithmetic number, because the mean of its divisors is an integer number (6325966875).

Almost surely, 2^21086556245 is an apocalyptic number.

It is an amenable number.

21086556245 is a deficient number, since it is larger than the sum of its proper divisors (4217311255).

21086556245 is an equidigital number, since it uses as much as digits as its factorization.

21086556245 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4217311254.

The product of its (nonzero) digits is 576000, while the sum is 44.

The spelling of 21086556245 in words is "twenty-one billion, eighty-six million, five hundred fifty-six thousand, two hundred forty-five".