21827191 has 2 divisors, whose sum is σ = 21827192. Its totient is φ = 21827190.

The previous prime is 21827177. The next prime is 21827233. The reversal of 21827191 is 19172812.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21827191 - 2⁷ = 21827063 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21827171) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10913595 + 10913596.

It is an arithmetic number, because the mean of its divisors is an integer number (10913596).

Almost surely, 2^21827191 is an apocalyptic number.

21827191 is a deficient number, since it is larger than the sum of its proper divisors (1).

21827191 is an equidigital number, since it uses as much as digits as its factorization.

21827191 is an evil number, because the sum of its binary digits is even.

The product of its digits is 2016, while the sum is 31.

The square root of 21827191 is about 4671.9579407353. The cubic root of 21827191 is about 279.4683406227.

The spelling of 21827191 in words is "twenty-one million, eight hundred twenty-seven thousand, one hundred ninety-one".