21331673 has 4 divisors (see below), whose sum is σ = 23270928. Its totient is φ = 19392420.

The previous prime is 21331669. The next prime is 21331679. The reversal of 21331673 is 37613312.

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 21331673 - 2² = 21331669 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21331679) 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, 969611 + ... + 969632.

It is an arithmetic number, because the mean of its divisors is an integer number (5817732).

Almost surely, 2^21331673 is an apocalyptic number.

It is an amenable number.

21331673 is a deficient number, since it is larger than the sum of its proper divisors (1939255).

21331673 is a wasteful number, since it uses less digits than its factorization.

21331673 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1939254.

The product of its digits is 2268, while the sum is 26.

The square root of 21331673 is about 4618.6224136641. The cubic root of 21331673 is about 277.3373144859.

Adding to 21331673 its reverse (37613312), we get a palindrome (58944985).

The spelling of 21331673 in words is "twenty-one million, three hundred thirty-one thousand, six hundred seventy-three".