20445947 has 2 divisors, whose sum is σ = 20445948. Its totient is φ = 20445946.

The previous prime is 20445923. The next prime is 20445949. The reversal of 20445947 is 74954402.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-20445947 is a prime.

Together with 20445949, 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 (20445949) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a good prime.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10222973 + 10222974.

It is an arithmetic number, because the mean of its divisors is an integer number (10222974).

Almost surely, 2^20445947 is an apocalyptic number.

20445947 is a deficient number, since it is larger than the sum of its proper divisors (1).

20445947 is an equidigital number, since it uses as much as digits as its factorization.

20445947 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 40320, while the sum is 35.

The square root of 20445947 is about 4521.7194738285. The cubic root of 20445947 is about 273.4444272117. Note that the first 4 decimals are identical.

The spelling of 20445947 in words is "twenty million, four hundred forty-five thousand, nine hundred forty-seven".