21091673 has 8 divisors (see below), whose sum is σ = 21610368. Its totient is φ = 20575984.

The previous prime is 21091663. The next prime is 21091703. The reversal of 21091673 is 37619012.

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 21091673 - 2²² = 16897369 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21091633) 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, 20315 + ... + 21327.

It is an arithmetic number, because the mean of its divisors is an integer number (2701296).

Almost surely, 2^21091673 is an apocalyptic number.

It is an amenable number.

21091673 is a deficient number, since it is larger than the sum of its proper divisors (518695).

21091673 is a wasteful number, since it uses less digits than its factorization.

21091673 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1503.

The product of its (nonzero) digits is 2268, while the sum is 29.

The square root of 21091673 is about 4592.5671470323. The cubic root of 21091673 is about 276.2932933793.

The spelling of 21091673 in words is "twenty-one million, ninety-one thousand, six hundred seventy-three".