21140491 has 4 divisors (see below), whose sum is σ = 21154672. Its totient is φ = 21126312.

The previous prime is 21140423. The next prime is 21140501. The reversal of 21140491 is 19404112.

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 21140491 - 2¹¹ = 21138443 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21140191) 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, 4551 + ... + 7936.

It is an arithmetic number, because the mean of its divisors is an integer number (5288668).

Almost surely, 2^21140491 is an apocalyptic number.

21140491 is a deficient number, since it is larger than the sum of its proper divisors (14181).

21140491 is a wasteful number, since it uses less digits than its factorization.

21140491 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 14180.

The product of its (nonzero) digits is 288, while the sum is 22.

The square root of 21140491 is about 4597.8789675240. The cubic root of 21140491 is about 276.5062951804.

The spelling of 21140491 in words is "twenty-one million, one hundred forty thousand, four hundred ninety-one".