21430191 has 4 divisors (see below), whose sum is σ = 28573592. Its totient is φ = 14286792.

The previous prime is 21430177. The next prime is 21430193. The reversal of 21430191 is 19103412.

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

It is not a de Polignac number, because 21430191 - 2⁷ = 21430063 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 (21430193) 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, 3571696 + ... + 3571701.

It is an arithmetic number, because the mean of its divisors is an integer number (7143398).

Almost surely, 2^21430191 is an apocalyptic number.

21430191 is a deficient number, since it is larger than the sum of its proper divisors (7143401).

21430191 is an equidigital number, since it uses as much as digits as its factorization.

21430191 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7143400.

The product of its (nonzero) digits is 216, while the sum is 21.

The square root of 21430191 is about 4629.2754292654. The cubic root of 21430191 is about 277.7636095825.

The spelling of 21430191 in words is "twenty-one million, four hundred thirty thousand, one hundred ninety-one".