21670873 has 4 divisors (see below), whose sum is σ = 24766720. Its totient is φ = 18575028.

The previous prime is 21670871. The next prime is 21670879. The reversal of 21670873 is 37807612.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 21670873 - 2¹ = 21670871 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21670871) 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, 1547913 + ... + 1547926.

It is an arithmetic number, because the mean of its divisors is an integer number (6191680).

Almost surely, 2^21670873 is an apocalyptic number.

It is an amenable number.

21670873 is a deficient number, since it is larger than the sum of its proper divisors (3095847).

21670873 is an equidigital number, since it uses as much as digits as its factorization.

21670873 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3095846.

The product of its (nonzero) digits is 14112, while the sum is 34.

The square root of 21670873 is about 4655.1984920087. The cubic root of 21670873 is about 278.7995931523.

The spelling of 21670873 in words is "twenty-one million, six hundred seventy thousand, eight hundred seventy-three".