21155555315 has 4 divisors (see below), whose sum is σ = 25386666384. Its totient is φ = 16924444248.

The previous prime is 21155555297. The next prime is 21155555321. The reversal of 21155555315 is 51355555112.

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

It is a cyclic number.

It is not a de Polignac number, because 21155555315 - 2¹⁰ = 21155554291 is a prime.

It is a Duffinian number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2115555527 + ... + 2115555536.

It is an arithmetic number, because the mean of its divisors is an integer number (6346666596).

Almost surely, 2^21155555315 is an apocalyptic number.

21155555315 is a deficient number, since it is larger than the sum of its proper divisors (4231111069).

21155555315 is an equidigital number, since it uses as much as digits as its factorization.

21155555315 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4231111068.

The product of its digits is 93750, while the sum is 38.

The spelling of 21155555315 in words is "twenty-one billion, one hundred fifty-five million, five hundred fifty-five thousand, three hundred fifteen".