20047921 has 2 divisors, whose sum is σ = 20047922. Its totient is φ = 20047920.

The previous prime is 20047919. The next prime is 20047943. The reversal of 20047921 is 12974002.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 10653696 + 9394225 = 3264^2 + 3065^2 .

It is a cyclic number.

It is not a de Polignac number, because 20047921 - 2¹ = 20047919 is a prime.

Together with 20047919, it forms a pair of twin primes.

It is not a weakly prime, because it can be changed into another prime (20047901) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10023960 + 10023961.

It is an arithmetic number, because the mean of its divisors is an integer number (10023961).

Almost surely, 2^20047921 is an apocalyptic number.

It is an amenable number.

20047921 is a deficient number, since it is larger than the sum of its proper divisors (1).

20047921 is an equidigital number, since it uses as much as digits as its factorization.

20047921 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 1008, while the sum is 25.

The square root of 20047921 is about 4477.4904801686. The cubic root of 20047921 is about 271.6583847493.

The spelling of 20047921 in words is "twenty million, forty-seven thousand, nine hundred twenty-one".