21398344855 has 4 divisors (see below), whose sum is σ = 25678013832. Its totient is φ = 17118675880.

The previous prime is 21398344819. The next prime is 21398344871. The reversal of 21398344855 is 55844389312.

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

It is not a de Polignac number, because 21398344855 - 2¹⁹ = 21397820567 is a prime.

It is a Duffinian number.

It is a congruent 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, 2139834481 + ... + 2139834490.

It is an arithmetic number, because the mean of its divisors is an integer number (6419503458).

Almost surely, 2^21398344855 is an apocalyptic number.

21398344855 is a deficient number, since it is larger than the sum of its proper divisors (4279668977).

21398344855 is an equidigital number, since it uses as much as digits as its factorization.

21398344855 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4279668976.

The product of its digits is 4147200, while the sum is 52.

The spelling of 21398344855 in words is "twenty-one billion, three hundred ninety-eight million, three hundred forty-four thousand, eight hundred fifty-five".