21171161340155 has 4 divisors (see below), whose sum is σ = 25405393608192. Its totient is φ = 16936929072120.

The previous prime is 21171161340143. The next prime is 21171161340167. The reversal of 21171161340155 is 55104316117112.

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

It is an interprime number because it is at equal distance from previous prime (21171161340143) and next prime (21171161340167).

It is not a de Polignac number, because 21171161340155 - 2²⁸ = 21170892904699 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, 2117116134011 + ... + 2117116134020.

It is an arithmetic number, because the mean of its divisors is an integer number (6351348402048).

Almost surely, 2^{21171161340155} is an apocalyptic number.

21171161340155 is a deficient number, since it is larger than the sum of its proper divisors (4234232268037).

21171161340155 is an equidigital number, since it uses as much as digits as its factorization.

21171161340155 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4234232268036.

The product of its (nonzero) digits is 25200, while the sum is 38.

Adding to 21171161340155 its reverse (55104316117112), we get a palindrome (76275477457267).

The spelling of 21171161340155 in words is "twenty-one trillion, one hundred seventy-one billion, one hundred sixty-one million, three hundred forty thousand, one hundred fifty-five".