21181417155 has 48 divisors (see below), whose sum is σ = 40214659680. Its totient is φ = 10265601024.

The previous prime is 21181417141. The next prime is 21181417177. The reversal of 21181417155 is 55171418112.

It is a happy number.

21181417155 is a `hidden beast` number, since 2 + 11 + 81 + 417 + 155 = 666.

It is not a de Polignac number, because 21181417155 - 2⁵ = 21181417123 is a prime.

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 47 ways as a sum of consecutive naturals, for example, 455197 + ... + 499566.

It is an arithmetic number, because the mean of its divisors is an integer number (837805410).

Almost surely, 2^21181417155 is an apocalyptic number.

21181417155 is a deficient number, since it is larger than the sum of its proper divisors (19033242525).

21181417155 is a wasteful number, since it uses less digits than its factorization.

21181417155 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 954820 (or 954817 counting only the distinct ones).

The product of its digits is 11200, while the sum is 36.

The spelling of 21181417155 in words is "twenty-one billion, one hundred eighty-one million, four hundred seventeen thousand, one hundred fifty-five".