21149841815 has 4 divisors (see below), whose sum is σ = 25379810184. Its totient is φ = 16919873448.

The previous prime is 21149841799. The next prime is 21149841863. The reversal of 21149841815 is 51814894112.

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 21149841815 - 2⁴ = 21149841799 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 3 ways as a sum of consecutive naturals, for example, 2114984177 + ... + 2114984186.

It is an arithmetic number, because the mean of its divisors is an integer number (6344952546).

Almost surely, 2^21149841815 is an apocalyptic number.

21149841815 is a deficient number, since it is larger than the sum of its proper divisors (4229968369).

21149841815 is an equidigital number, since it uses as much as digits as its factorization.

21149841815 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4229968368.

The product of its digits is 92160, while the sum is 44.

The spelling of 21149841815 in words is "twenty-one billion, one hundred forty-nine million, eight hundred forty-one thousand, eight hundred fifteen".