20981473 has 2 divisors, whose sum is σ = 20981474. Its totient is φ = 20981472.

The previous prime is 20981461. The next prime is 20981507. The reversal of 20981473 is 37418902.

It is an a-pointer prime, because the next prime (20981507) can be obtained adding 20981473 to its sum of digits (34).

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 14386849 + 6594624 = 3793^2 + 2568^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-20981473 is a prime.

It is not a weakly prime, because it can be changed into another prime (20981273) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10490736 + 10490737.

It is an arithmetic number, because the mean of its divisors is an integer number (10490737).

Almost surely, 2^20981473 is an apocalyptic number.

It is an amenable number.

20981473 is a deficient number, since it is larger than the sum of its proper divisors (1).

20981473 is an equidigital number, since it uses as much as digits as its factorization.

20981473 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 12096, while the sum is 34.

The square root of 20981473 is about 4580.5537874803. The cubic root of 20981473 is about 275.8112594995.

The spelling of 20981473 in words is "twenty million, nine hundred eighty-one thousand, four hundred seventy-three".