21673871 has 4 divisors (see below), whose sum is σ = 22202544. Its totient is φ = 21145200.

The previous prime is 21673859. The next prime is 21673921. The reversal of 21673871 is 17837612.

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 21673871 - 2⁶ = 21673807 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 (21673831) 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, 264275 + ... + 264356.

It is an arithmetic number, because the mean of its divisors is an integer number (5550636).

Almost surely, 2^21673871 is an apocalyptic number.

21673871 is a deficient number, since it is larger than the sum of its proper divisors (528673).

21673871 is an equidigital number, since it uses as much as digits as its factorization.

21673871 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 528672.

The product of its digits is 14112, while the sum is 35.

The square root of 21673871 is about 4655.5204864762. The cubic root of 21673871 is about 278.8124491586.

The spelling of 21673871 in words is "twenty-one million, six hundred seventy-three thousand, eight hundred seventy-one".