21670243 has 8 divisors (see below), whose sum is σ = 25293312. Its totient is φ = 18179016.

The previous prime is 21670219. The next prime is 21670283. The reversal of 21670243 is 34207612.

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 21670243 - 2⁵ = 21670211 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21670213) 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, 32605 + ... + 33262.

It is an arithmetic number, because the mean of its divisors is an integer number (3161664).

Almost surely, 2^21670243 is an apocalyptic number.

21670243 is a deficient number, since it is larger than the sum of its proper divisors (3623069).

21670243 is an equidigital number, since it uses as much as digits as its factorization.

21670243 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 65921.

The product of its (nonzero) digits is 2016, while the sum is 25.

The square root of 21670243 is about 4655.1308252293. The cubic root of 21670243 is about 278.7968914392.

Adding to 21670243 its reverse (34207612), we get a palindrome (55877855).

The spelling of 21670243 in words is "twenty-one million, six hundred seventy thousand, two hundred forty-three".