643091917 has 16 divisors (see below), whose sum is σ = 741384000. Its totient is φ = 552835584.

The previous prime is 643091903. The next prime is 643091921. The reversal of 643091917 is 719190346.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-643091917 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 643091917.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (643091987) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 7492 + ... + 36637.

It is an arithmetic number, because the mean of its divisors is an integer number (46336500).

Almost surely, 2^643091917 is an apocalyptic number.

It is an amenable number.

643091917 is a deficient number, since it is larger than the sum of its proper divisors (98292083).

643091917 is a wasteful number, since it uses less digits than its factorization.

643091917 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 44220.

The product of its (nonzero) digits is 40824, while the sum is 40.

The square root of 643091917 is about 25359.2570277601. The cubic root of 643091917 is about 863.1594249103.

The spelling of 643091917 in words is "six hundred forty-three million, ninety-one thousand, nine hundred seventeen".