21907191 has 8 divisors (see below), whose sum is σ = 29645824. Its totient is φ = 14386680.

The previous prime is 21907189. The next prime is 21907229. The reversal of 21907191 is 19170912.

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

It is not a de Polignac number, because 21907191 - 2¹ = 21907189 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21902191) 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, 54295 + ... + 54696.

It is an arithmetic number, because the mean of its divisors is an integer number (3705728).

Almost surely, 2^21907191 is an apocalyptic number.

21907191 is a deficient number, since it is larger than the sum of its proper divisors (7738633).

21907191 is a wasteful number, since it uses less digits than its factorization.

21907191 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 109061.

The product of its (nonzero) digits is 1134, while the sum is 30.

The square root of 21907191 is about 4680.5118309860. The cubic root of 21907191 is about 279.8093557693.

The spelling of 21907191 in words is "twenty-one million, nine hundred seven thousand, one hundred ninety-one".