20847971 has 2 divisors, whose sum is σ = 20847972. Its totient is φ = 20847970.

The previous prime is 20847949. The next prime is 20847973. The reversal of 20847971 is 17974802.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-20847971 is a prime.

Together with 20847973, 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 (20847973) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10423985 + 10423986.

It is an arithmetic number, because the mean of its divisors is an integer number (10423986).

Almost surely, 2^20847971 is an apocalyptic number.

20847971 is a deficient number, since it is larger than the sum of its proper divisors (1).

20847971 is an equidigital number, since it uses as much as digits as its factorization.

20847971 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 28224, while the sum is 38.

The square root of 20847971 is about 4565.9578403660. The cubic root of 20847971 is about 275.2250323349.

The spelling of 20847971 in words is "twenty million, eight hundred forty-seven thousand, nine hundred seventy-one".