21313391 has 8 divisors (see below), whose sum is σ = 23395584. Its totient is φ = 19255320.

The previous prime is 21313379. The next prime is 21313429. The reversal of 21313391 is 19331312.

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 21313391 - 2²² = 17119087 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 (21313301) 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, 4151 + ... + 7736.

It is an arithmetic number, because the mean of its divisors is an integer number (2924448).

Almost surely, 2^21313391 is an apocalyptic number.

21313391 is a deficient number, since it is larger than the sum of its proper divisors (2082193).

21313391 is a wasteful number, since it uses less digits than its factorization.

21313391 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 12061.

The product of its digits is 486, while the sum is 23.

The square root of 21313391 is about 4616.6428278566. The cubic root of 21313391 is about 277.2580625375.

The spelling of 21313391 in words is "twenty-one million, three hundred thirteen thousand, three hundred ninety-one".