643729197 has 4 divisors (see below), whose sum is σ = 858305600. Its totient is φ = 429152796.

The previous prime is 643729193. The next prime is 643729199. The reversal of 643729197 is 791927346.

It is a happy number.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is not a de Polignac number, because 643729197 - 2² = 643729193 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 (643729193) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 107288197 + ... + 107288202.

It is an arithmetic number, because the mean of its divisors is an integer number (214576400).

Almost surely, 2^643729197 is an apocalyptic number.

It is an amenable number.

643729197 is a deficient number, since it is larger than the sum of its proper divisors (214576403).

643729197 is a wasteful number, since it uses less digits than its factorization.

643729197 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 214576402.

The product of its digits is 571536, while the sum is 48.

The square root of 643729197 is about 25371.8189533191. The cubic root of 643729197 is about 863.4444503335. Note that the first 4 decimals are identical.

The spelling of 643729197 in words is "six hundred forty-three million, seven hundred twenty-nine thousand, one hundred ninety-seven".