21427447 has 2 divisors, whose sum is σ = 21427448. Its totient is φ = 21427446.

The previous prime is 21427381. The next prime is 21427451. The reversal of 21427447 is 74472412.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21427447 - 2⁷ = 21427319 is a prime.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21427457) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10713723 + 10713724.

It is an arithmetic number, because the mean of its divisors is an integer number (10713724).

Almost surely, 2^21427447 is an apocalyptic number.

21427447 is a deficient number, since it is larger than the sum of its proper divisors (1).

21427447 is an equidigital number, since it uses as much as digits as its factorization.

21427447 is an evil number, because the sum of its binary digits is even.

The product of its digits is 12544, while the sum is 31.

The square root of 21427447 is about 4628.9790451027. The cubic root of 21427447 is about 277.7517537872.

Adding to 21427447 its reverse (74472412), we get a palindrome (95899859).

The spelling of 21427447 in words is "twenty-one million, four hundred twenty-seven thousand, four hundred forty-seven".