21367391 has 8 divisors (see below), whose sum is σ = 22349184. Its totient is φ = 20390040.

The previous prime is 21367331. The next prime is 21367393. The reversal of 21367391 is 19376312.

It is a happy number.

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 21367391 - 2¹⁴ = 21351007 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 (21367393) 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, 12320 + ... + 13946.

It is an arithmetic number, because the mean of its divisors is an integer number (2793648).

Almost surely, 2^21367391 is an apocalyptic number.

21367391 is a deficient number, since it is larger than the sum of its proper divisors (981793).

21367391 is a wasteful number, since it uses less digits than its factorization.

21367391 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2221.

The product of its digits is 6804, while the sum is 32.

The square root of 21367391 is about 4622.4875337852. The cubic root of 21367391 is about 277.4920204399.

The spelling of 21367391 in words is "twenty-one million, three hundred sixty-seven thousand, three hundred ninety-one".