21560191 has 4 divisors (see below), whose sum is σ = 21662584. Its totient is φ = 21457800.

The previous prime is 21560171. The next prime is 21560197. The reversal of 21560191 is 19106512.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 21560191 - 2¹¹ = 21558143 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 (21560197) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 50880 + ... + 51301.

It is an arithmetic number, because the mean of its divisors is an integer number (5415646).

Almost surely, 2^21560191 is an apocalyptic number.

21560191 is a deficient number, since it is larger than the sum of its proper divisors (102393).

21560191 is a wasteful number, since it uses less digits than its factorization.

21560191 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 102392.

The product of its (nonzero) digits is 540, while the sum is 25.

The square root of 21560191 is about 4643.2952738330. The cubic root of 21560191 is about 278.3241349783.

It can be divided in two parts, 215 and 60191, that added together give a palindrome (60406).

The spelling of 21560191 in words is "twenty-one million, five hundred sixty thousand, one hundred ninety-one".