645110989 has 2 divisors, whose sum is σ = 645110990. Its totient is φ = 645110988.

The previous prime is 645110981. The next prime is 645111007. The reversal of 645110989 is 989011546.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 463670089 + 181440900 = 21533^2 + 13470^2 .

It is a cyclic number.

It is not a de Polignac number, because 645110989 - 2³ = 645110981 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (645110981) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 322555494 + 322555495.

It is an arithmetic number, because the mean of its divisors is an integer number (322555495).

Almost surely, 2^645110989 is an apocalyptic number.

It is an amenable number.

645110989 is a deficient number, since it is larger than the sum of its proper divisors (1).

645110989 is an equidigital number, since it uses as much as digits as its factorization.

645110989 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 77760, while the sum is 43.

The square root of 645110989 is about 25399.0351982118. The cubic root of 645110989 is about 864.0618155111.

The spelling of 645110989 in words is "six hundred forty-five million, one hundred ten thousand, nine hundred eighty-nine".