21430291 has 2 divisors, whose sum is σ = 21430292. Its totient is φ = 21430290.

The previous prime is 21430259. The next prime is 21430301. The reversal of 21430291 is 19203412.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21430291 - 2⁵ = 21430259 is a prime.

It is not a weakly prime, because it can be changed into another prime (21430091) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10715145 + 10715146.

It is an arithmetic number, because the mean of its divisors is an integer number (10715146).

Almost surely, 2^21430291 is an apocalyptic number.

21430291 is a deficient number, since it is larger than the sum of its proper divisors (1).

21430291 is an equidigital number, since it uses as much as digits as its factorization.

21430291 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 432, while the sum is 22.

The square root of 21430291 is about 4629.2862300791. The cubic root of 21430291 is about 277.7640416259.

The spelling of 21430291 in words is "twenty-one million, four hundred thirty thousand, two hundred ninety-one".