645466817 has 4 divisors (see below), whose sum is σ = 647093076. Its totient is φ = 643840560.

The previous prime is 645466793. The next prime is 645466837. The reversal of 645466817 is 718664546.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 284124736 + 361342081 = 16856^2 + 19009^2 .

It is a cyclic number.

It is not a de Polignac number, because 645466817 - 2⁶ = 645466753 is a prime.

It is a super-2 number, since 2×645466817² = 833254823696222978, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (645466837) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 812534 + ... + 813327.

It is an arithmetic number, because the mean of its divisors is an integer number (161773269).

Almost surely, 2^645466817 is an apocalyptic number.

It is an amenable number.

645466817 is a deficient number, since it is larger than the sum of its proper divisors (1626259).

645466817 is a wasteful number, since it uses less digits than its factorization.

645466817 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1626258.

The product of its digits is 967680, while the sum is 47.

The square root of 645466817 is about 25406.0389868236. The cubic root of 645466817 is about 864.2206516812.

The spelling of 645466817 in words is "six hundred forty-five million, four hundred sixty-six thousand, eight hundred seventeen".