21389965 has 8 divisors (see below), whose sum is σ = 26553240. Its totient is φ = 16521792.

The previous prime is 21389941. The next prime is 21389971. The reversal of 21389965 is 56998312.

It is a happy number.

It can be written as a sum of positive squares in 4 ways, for example, as 2223081 + 19166884 = 1491^2 + 4378^2 .

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 21389965 - 2⁵ = 21389933 is a prime.

It is a congruent number.

It is an unprimeable number.

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, 73614 + ... + 73903.

It is an arithmetic number, because the mean of its divisors is an integer number (3319155).

Almost surely, 2^21389965 is an apocalyptic number.

It is an amenable number.

21389965 is a deficient number, since it is larger than the sum of its proper divisors (5163275).

21389965 is a wasteful number, since it uses less digits than its factorization.

21389965 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 147551.

The product of its digits is 116640, while the sum is 43.

The square root of 21389965 is about 4624.9286480983. The cubic root of 21389965 is about 277.5897066793.

The spelling of 21389965 in words is "twenty-one million, three hundred eighty-nine thousand, nine hundred sixty-five".