21391107 has 8 divisors (see below), whose sum is σ = 28665600. Its totient is φ = 14188680.

The previous prime is 21391091. The next prime is 21391129. The reversal of 21391107 is 70119312.

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

It is not a de Polignac number, because 21391107 - 2⁴ = 21391091 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21391187) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 17319 + ... + 18512.

It is an arithmetic number, because the mean of its divisors is an integer number (3583200).

Almost surely, 2^21391107 is an apocalyptic number.

21391107 is a deficient number, since it is larger than the sum of its proper divisors (7274493).

21391107 is a wasteful number, since it uses less digits than its factorization.

21391107 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 36033.

The product of its (nonzero) digits is 378, while the sum is 24.

The square root of 21391107 is about 4625.0521078146. The cubic root of 21391107 is about 277.5946467186.

The spelling of 21391107 in words is "twenty-one million, three hundred ninety-one thousand, one hundred seven".