643744663 has 4 divisors (see below), whose sum is σ = 643821640. Its totient is φ = 643667688.

The previous prime is 643744657. The next prime is 643744679. The reversal of 643744663 is 366447346.

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

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-643744663 is a prime.

It is a super-2 number, since 2×643744663² = 828814382281967138, 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 (643744603) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 24168 + ... + 43261.

It is an arithmetic number, because the mean of its divisors is an integer number (160955410).

Almost surely, 2^643744663 is an apocalyptic number.

643744663 is a deficient number, since it is larger than the sum of its proper divisors (76977).

643744663 is an equidigital number, since it uses as much as digits as its factorization.

643744663 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 76976.

The product of its digits is 870912, while the sum is 43.

The square root of 643744663 is about 25372.1237384654. The cubic root of 643744663 is about 863.4513652106.

The spelling of 643744663 in words is "six hundred forty-three million, seven hundred forty-four thousand, six hundred sixty-three".