21167421 has 8 divisors (see below), whose sum is σ = 30789024. Its totient is φ = 12828720.

The previous prime is 21167413. The next prime is 21167423. The reversal of 21167421 is 12476112.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 21167421 - 2³ = 21167413 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 21167391 and 21167400.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21167423) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 320686 + ... + 320751.

It is an arithmetic number, because the mean of its divisors is an integer number (3848628).

Almost surely, 2^21167421 is an apocalyptic number.

It is an amenable number.

21167421 is a deficient number, since it is larger than the sum of its proper divisors (9621603).

21167421 is a wasteful number, since it uses less digits than its factorization.

21167421 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 641451.

The product of its digits is 672, while the sum is 24.

The square root of 21167421 is about 4600.8065597241. The cubic root of 21167421 is about 276.6236553514.

The spelling of 21167421 in words is "twenty-one million, one hundred sixty-seven thousand, four hundred twenty-one".