21221012167 has 4 divisors (see below), whose sum is σ = 21221317816. Its totient is φ = 21220706520.

The previous prime is 21221012119. The next prime is 21221012177. The reversal of 21221012167 is 76121012212.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It is a cyclic number.

It is not a de Polignac number, because 21221012167 - 2²⁷ = 21086794439 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 (21221012177) 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, 7117 + ... + 206137.

It is an arithmetic number, because the mean of its divisors is an integer number (5305329454).

Almost surely, 2^21221012167 is an apocalyptic number.

21221012167 is a deficient number, since it is larger than the sum of its proper divisors (305649).

21221012167 is a wasteful number, since it uses less digits than its factorization.

21221012167 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 305648.

The product of its (nonzero) digits is 672, while the sum is 25.

Adding to 21221012167 its reverse (76121012212), we get a palindrome (97342024379).

The spelling of 21221012167 in words is "twenty-one billion, two hundred twenty-one million, twelve thousand, one hundred sixty-seven".