645554669 has 2 divisors, whose sum is σ = 645554670. Its totient is φ = 645554668.

The previous prime is 645554603. The next prime is 645554671. The reversal of 645554669 is 966455546.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 593166025 + 52388644 = 24355^2 + 7238^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-645554669 is a prime.

It is a super-2 number, since 2×645554669² = 833481661335399122, which contains 22 as substring.

Together with 645554671, it forms a pair of twin primes.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (645554069) 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, 322777334 + 322777335.

It is an arithmetic number, because the mean of its divisors is an integer number (322777335).

Almost surely, 2^645554669 is an apocalyptic number.

It is an amenable number.

645554669 is a deficient number, since it is larger than the sum of its proper divisors (1).

645554669 is an equidigital number, since it uses as much as digits as its factorization.

645554669 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 3888000, while the sum is 50.

The square root of 645554669 is about 25407.7678870065. The cubic root of 645554669 is about 864.2598584828.

The spelling of 645554669 in words is "six hundred forty-five million, five hundred fifty-four thousand, six hundred sixty-nine".