21369391 has 8 divisors (see below), whose sum is σ = 22861440. Its totient is φ = 19903488.

The previous prime is 21369389. The next prime is 21369407. The reversal of 21369391 is 19396312.

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 21369391 - 2¹ = 21369389 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 (21369311) 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, 4831 + ... + 8128.

It is an arithmetic number, because the mean of its divisors is an integer number (2857680).

Almost surely, 2^21369391 is an apocalyptic number.

21369391 is a deficient number, since it is larger than the sum of its proper divisors (1492049).

21369391 is a wasteful number, since it uses less digits than its factorization.

21369391 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 13073.

The product of its digits is 8748, while the sum is 34.

The square root of 21369391 is about 4622.7038624597. The cubic root of 21369391 is about 277.5006779736.

The spelling of 21369391 in words is "twenty-one million, three hundred sixty-nine thousand, three hundred ninety-one".