20985847 has 2 divisors, whose sum is σ = 20985848. Its totient is φ = 20985846.

The previous prime is 20985799. The next prime is 20985857. The reversal of 20985847 is 74858902.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 20985847 - 2¹¹ = 20983799 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (20985857) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10492923 + 10492924.

It is an arithmetic number, because the mean of its divisors is an integer number (10492924).

Almost surely, 2^20985847 is an apocalyptic number.

20985847 is a deficient number, since it is larger than the sum of its proper divisors (1).

20985847 is an equidigital number, since it uses as much as digits as its factorization.

20985847 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 161280, while the sum is 43.

The square root of 20985847 is about 4581.0312157854. The cubic root of 20985847 is about 275.8304242586.

The spelling of 20985847 in words is "twenty million, nine hundred eighty-five thousand, eight hundred forty-seven".