21155167 has 4 divisors (see below), whose sum is σ = 23078376. Its totient is φ = 19231960.

The previous prime is 21155161. The next prime is 21155171. The reversal of 21155167 is 76155112.

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

It is not a de Polignac number, because 21155167 - 2³ = 21155159 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21155161) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 961588 + ... + 961609.

It is an arithmetic number, because the mean of its divisors is an integer number (5769594).

Almost surely, 2^21155167 is an apocalyptic number.

21155167 is a deficient number, since it is larger than the sum of its proper divisors (1923209).

21155167 is a wasteful number, since it uses less digits than its factorization.

21155167 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1923208.

The product of its digits is 2100, while the sum is 28.

The square root of 21155167 is about 4599.4746439132. The cubic root of 21155167 is about 276.5702651187.

Subtracting 21155167 from its reverse (76155112), we obtain a palindrome (54999945).

The spelling of 21155167 in words is "twenty-one million, one hundred fifty-five thousand, one hundred sixty-seven".