643817693 has 8 divisors (see below), whose sum is σ = 681967800. Its totient is φ = 605698560.

The previous prime is 643817687. The next prime is 643817701. The reversal of 643817693 is 396718346.

It is a happy number.

It can be written as a sum of positive squares in 4 ways, for example, as 216031204 + 427786489 = 14698^2 + 20683^2 .

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 643817693 - 2⁴ = 643817677 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 (643817623) 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, 45623 + ... + 58043.

It is an arithmetic number, because the mean of its divisors is an integer number (85245975).

Almost surely, 2^643817693 is an apocalyptic number.

It is an amenable number.

643817693 is a deficient number, since it is larger than the sum of its proper divisors (38150107).

643817693 is a wasteful number, since it uses less digits than its factorization.

643817693 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 15487.

The product of its digits is 653184, while the sum is 47.

The square root of 643817693 is about 25373.5628755601. The cubic root of 643817693 is about 863.4840155622.

The spelling of 643817693 in words is "six hundred forty-three million, eight hundred seventeen thousand, six hundred ninety-three".