21191365 has 16 divisors (see below), whose sum is σ = 28828800. Its totient is φ = 14824512.

The previous prime is 21191341. The next prime is 21191369. The reversal of 21191365 is 56319112.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21191365 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21191369) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 7345 + ... + 9814.

It is an arithmetic number, because the mean of its divisors is an integer number (1801800).

Almost surely, 2^21191365 is an apocalyptic number.

It is an amenable number.

21191365 is a deficient number, since it is larger than the sum of its proper divisors (7637435).

21191365 is a wasteful number, since it uses less digits than its factorization.

21191365 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 17196.

The product of its digits is 1620, while the sum is 28.

The square root of 21191365 is about 4603.4079767060. The cubic root of 21191365 is about 276.7279190521.

The spelling of 21191365 in words is "twenty-one million, one hundred ninety-one thousand, three hundred sixty-five".