21551167 has 4 divisors (see below), whose sum is σ = 23510376. Its totient is φ = 19591960.

The previous prime is 21551143. The next prime is 21551171. The reversal of 21551167 is 76115512.

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 21551167 - 2⁷ = 21551039 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 (21551137) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 979588 + ... + 979609.

It is an arithmetic number, because the mean of its divisors is an integer number (5877594).

Almost surely, 2^21551167 is an apocalyptic number.

21551167 is a deficient number, since it is larger than the sum of its proper divisors (1959209).

21551167 is a wasteful number, since it uses less digits than its factorization.

21551167 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1959208.

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

The square root of 21551167 is about 4642.3234484469. The cubic root of 21551167 is about 278.2852987812.

Adding to 21551167 its reverse (76115512), we get a palindrome (97666679).

The spelling of 21551167 in words is "twenty-one million, five hundred fifty-one thousand, one hundred sixty-seven".