21672305 has 8 divisors (see below), whose sum is σ = 26055744. Its totient is φ = 17305200.

The previous prime is 21672271. The next prime is 21672319. The reversal of 21672305 is 50327612.

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

It is a de Polignac number, because none of the positive numbers 2^k-21672305 is a prime.

It is an alternating number because its digits alternate between even and odd.

It is a Duffinian number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 941 + ... + 6650.

It is an arithmetic number, because the mean of its divisors is an integer number (3256968).

Almost surely, 2^21672305 is an apocalyptic number.

It is an amenable number.

21672305 is a deficient number, since it is larger than the sum of its proper divisors (4383439).

21672305 is an equidigital number, since it uses as much as digits as its factorization.

21672305 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 8167.

The product of its (nonzero) digits is 2520, while the sum is 26.

The square root of 21672305 is about 4655.3522960137. The cubic root of 21672305 is about 278.8057339943.

Adding to 21672305 its reverse (50327612), we get a palindrome (71999917).

The spelling of 21672305 in words is "twenty-one million, six hundred seventy-two thousand, three hundred five".