645651917 has 8 divisors (see below), whose sum is σ = 649296000. Its totient is φ = 642017584.

The previous prime is 645651913. The next prime is 645651943. The reversal of 645651917 is 719156546.

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 645651917 - 2² = 645651913 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (645651913) 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, 159128 + ... + 163134.

It is an arithmetic number, because the mean of its divisors is an integer number (81162000).

Almost surely, 2^645651917 is an apocalyptic number.

It is an amenable number.

645651917 is a deficient number, since it is larger than the sum of its proper divisors (3644083).

645651917 is a wasteful number, since it uses less digits than its factorization.

645651917 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4875.

The product of its digits is 226800, while the sum is 44.

The square root of 645651917 is about 25409.6815603817. The cubic root of 645651917 is about 864.3032544061.

The spelling of 645651917 in words is "six hundred forty-five million, six hundred fifty-one thousand, nine hundred seventeen".