643157 has 4 divisors (see below), whose sum is σ = 663936. Its totient is φ = 622380.

The previous prime is 643129. The next prime is 643183. The reversal of 643157 is 751346.

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, and also an emirpimes, since its reverse is a distinct semiprime: 751346 = 2 ⋅375673.

It is a cyclic number.

It is not a de Polignac number, because 643157 - 2¹⁰ = 642133 is a prime.

It is a Duffinian number.

It is a nialpdrome in base 15.

It is a congruent number.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 643157.

It is not an unprimeable number, because it can be changed into a prime (643187) 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, 10343 + ... + 10404.

It is an arithmetic number, because the mean of its divisors is an integer number (165984).

2⁶⁴³¹⁵⁷ is an apocalyptic number.

It is an amenable number.

643157 is a deficient number, since it is larger than the sum of its proper divisors (20779).

643157 is a wasteful number, since it uses less digits than its factorization.

643157 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 20778.

The product of its digits is 2520, while the sum is 26.

The square root of 643157 is about 801.9706977191. The cubic root of 643157 is about 86.3188542111.

The spelling of 643157 in words is "six hundred forty-three thousand, one hundred fifty-seven".