645880189 has 2 divisors, whose sum is σ = 645880190. Its totient is φ = 645880188.

The previous prime is 645880163. The next prime is 645880211. The reversal of 645880189 is 981088546.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 386122500 + 259757689 = 19650^2 + 16117^2 .

It is a cyclic number.

It is not a de Polignac number, because 645880189 - 2²³ = 637491581 is a prime.

It is a super-2 number, since 2×645880189² = 834322437085351442, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (645880289) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 322940094 + 322940095.

It is an arithmetic number, because the mean of its divisors is an integer number (322940095).

Almost surely, 2^645880189 is an apocalyptic number.

It is an amenable number.

645880189 is a deficient number, since it is larger than the sum of its proper divisors (1).

645880189 is an equidigital number, since it uses as much as digits as its factorization.

645880189 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 552960, while the sum is 49.

The square root of 645880189 is about 25414.1729946107. The cubic root of 645880189 is about 864.4051013303.

The spelling of 645880189 in words is "six hundred forty-five million, eight hundred eighty thousand, one hundred eighty-nine".