21027947 has 2 divisors, whose sum is σ = 21027948. Its totient is φ = 21027946.

The previous prime is 21027943. The next prime is 21027949. The reversal of 21027947 is 74972012.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21027947 - 2² = 21027943 is a prime.

Together with 21027949, it forms a pair of twin primes.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (21027943) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10513973 + 10513974.

It is an arithmetic number, because the mean of its divisors is an integer number (10513974).

Almost surely, 2^21027947 is an apocalyptic number.

21027947 is a deficient number, since it is larger than the sum of its proper divisors (1).

21027947 is an equidigital number, since it uses as much as digits as its factorization.

21027947 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 7056, while the sum is 32.

The square root of 21027947 is about 4585.6239488209. The cubic root of 21027947 is about 276.0147501394.

Adding to 21027947 its reverse (74972012), we get a palindrome (95999959).

The spelling of 21027947 in words is "twenty-one million, twenty-seven thousand, nine hundred forty-seven".