21173421 has 8 divisors (see below), whose sum is σ = 28253664. Its totient is φ = 14104400.

The previous prime is 21173419. The next prime is 21173423. The reversal of 21173421 is 12437112.

It is an interprime number because it is at equal distance from previous prime (21173419) and next prime (21173423).

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

It is a cyclic number.

It is not a de Polignac number, because 21173421 - 2¹ = 21173419 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21173423) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 3871 + ... + 7571.

It is an arithmetic number, because the mean of its divisors is an integer number (3531708).

Almost surely, 2^21173421 is an apocalyptic number.

It is an amenable number.

21173421 is a deficient number, since it is larger than the sum of its proper divisors (7080243).

21173421 is a wasteful number, since it uses less digits than its factorization.

21173421 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5611.

The product of its digits is 336, while the sum is 21.

The square root of 21173421 is about 4601.4585731048. The cubic root of 21173421 is about 276.6497896190.

The spelling of 21173421 in words is "twenty-one million, one hundred seventy-three thousand, four hundred twenty-one".