21159191 has 4 divisors (see below), whose sum is σ = 21215400. Its totient is φ = 21102984.

The previous prime is 21159181. The next prime is 21159211. The reversal of 21159191 is 19195112.

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 21159191 - 2¹⁸ = 20897047 is a prime.

It is a super-2 number, since 2×21159191² = 895422727548962, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21159121) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 27536 + ... + 28293.

It is an arithmetic number, because the mean of its divisors is an integer number (5303850).

Almost surely, 2^21159191 is an apocalyptic number.

21159191 is a deficient number, since it is larger than the sum of its proper divisors (56209).

21159191 is an equidigital number, since it uses as much as digits as its factorization.

21159191 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 56208.

The product of its digits is 810, while the sum is 29.

The square root of 21159191 is about 4599.9120643769. The cubic root of 21159191 is about 276.5877998135.

The spelling of 21159191 in words is "twenty-one million, one hundred fifty-nine thousand, one hundred ninety-one".