201645989 has 2 divisors, whose sum is σ = 201645990. Its totient is φ = 201645988.

The previous prime is 201645971. The next prime is 201646001. The reversal of 201645989 is 989546102.

201645989 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 155201764 + 46444225 = 12458^2 + 6815^2 .

It is a cyclic number.

It is not a de Polignac number, because 201645989 - 2⁸ = 201645733 is a prime.

It is a super-2 number, since 2×201645989² = 81322209759576242, which contains 22 as substring.

It is a Sophie Germain prime.

It is a Curzon number.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (201645289) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 100822994 + 100822995.

It is an arithmetic number, because the mean of its divisors is an integer number (100822995).

Almost surely, 2^201645989 is an apocalyptic number.

It is an amenable number.

201645989 is a deficient number, since it is larger than the sum of its proper divisors (1).

201645989 is an equidigital number, since it uses as much as digits as its factorization.

201645989 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 155520, while the sum is 44.

The square root of 201645989 is about 14200.2108787159. The cubic root of 201645989 is about 586.4034668986.

The spelling of 201645989 in words is "two hundred one million, six hundred forty-five thousand, nine hundred eighty-nine".