21391105 has 8 divisors (see below), whose sum is σ = 25768512. Its totient is φ = 17046768.

The previous prime is 21391091. The next prime is 21391129. The reversal of 21391105 is 50119312.

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 21391105 - 2⁷ = 21390977 is a prime.

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, 6819 + ... + 9448.

It is an arithmetic number, because the mean of its divisors is an integer number (3221064).

Almost surely, 2^21391105 is an apocalyptic number.

It is an amenable number.

21391105 is a deficient number, since it is larger than the sum of its proper divisors (4377407).

21391105 is a wasteful number, since it uses less digits than its factorization.

21391105 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 16535.

The product of its (nonzero) digits is 270, while the sum is 22.

The square root of 21391105 is about 4625.0518916008. The cubic root of 21391105 is about 277.5946380672.

The spelling of 21391105 in words is "twenty-one million, three hundred ninety-one thousand, one hundred five".