21421427 has 2 divisors, whose sum is σ = 21421428. Its totient is φ = 21421426.

The previous prime is 21421399. The next prime is 21421451. The reversal of 21421427 is 72412412.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21421427 - 2¹⁰ = 21420403 is a prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (21421627) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10710713 + 10710714.

It is an arithmetic number, because the mean of its divisors is an integer number (10710714).

Almost surely, 2^21421427 is an apocalyptic number.

21421427 is a deficient number, since it is larger than the sum of its proper divisors (1).

21421427 is an equidigital number, since it uses as much as digits as its factorization.

21421427 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 896, while the sum is 23.

The square root of 21421427 is about 4628.3287480472. The cubic root of 21421427 is about 277.7257400773.

Adding to 21421427 its reverse (72412412), we get a palindrome (93833839).

The spelling of 21421427 in words is "twenty-one million, four hundred twenty-one thousand, four hundred twenty-seven".