645918917 has 8 divisors (see below), whose sum is σ = 740803776. Its totient is φ = 551686752.

The previous prime is 645918907. The next prime is 645918929. The reversal of 645918917 is 719819546.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 645918917 - 2⁴ = 645918901 is a prime.

It is a super-2 number, since 2×645918917² = 834422494676905778, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (645918907) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 161048 + ... + 165009.

It is an arithmetic number, because the mean of its divisors is an integer number (92600472).

Almost surely, 2^645918917 is an apocalyptic number.

It is an amenable number.

645918917 is a deficient number, since it is larger than the sum of its proper divisors (94884859).

645918917 is a wasteful number, since it uses less digits than its factorization.

645918917 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 326347.

The product of its digits is 544320, while the sum is 50.

The square root of 645918917 is about 25414.9349202393. The cubic root of 645918917 is about 864.4223780184.

The spelling of 645918917 in words is "six hundred forty-five million, nine hundred eighteen thousand, nine hundred seventeen".