21246191 has 4 divisors (see below), whose sum is σ = 21931584. Its totient is φ = 20560800.

The previous prime is 21246187. The next prime is 21246193. The reversal of 21246191 is 19164212.

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 21246191 - 2² = 21246187 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 21246191.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21246193) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 342650 + ... + 342711.

It is an arithmetic number, because the mean of its divisors is an integer number (5482896).

Almost surely, 2^21246191 is an apocalyptic number.

21246191 is a deficient number, since it is larger than the sum of its proper divisors (685393).

21246191 is an equidigital number, since it uses as much as digits as its factorization.

21246191 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 685392.

The product of its digits is 864, while the sum is 26.

The square root of 21246191 is about 4609.3590660742. The cubic root of 21246191 is about 276.9663623913.

The spelling of 21246191 in words is "twenty-one million, two hundred forty-six thousand, one hundred ninety-one".