643543157 has 4 divisors (see below), whose sum is σ = 647642316. Its totient is φ = 639444000.

The previous prime is 643543123. The next prime is 643543171. The reversal of 643543157 is 751345346.

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

It can be written as a sum of positive squares in 2 ways, for example, as 153983281 + 489559876 = 12409^2 + 22126^2 .

It is a cyclic number.

It is not a de Polignac number, because 643543157 - 2²⁸ = 375107701 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 643543157.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (643543057) 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, 2049344 + ... + 2049657.

It is an arithmetic number, because the mean of its divisors is an integer number (161910579).

Almost surely, 2^643543157 is an apocalyptic number.

It is an amenable number.

643543157 is a deficient number, since it is larger than the sum of its proper divisors (4099159).

643543157 is a wasteful number, since it uses less digits than its factorization.

643543157 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4099158.

The product of its digits is 151200, while the sum is 38.

The square root of 643543157 is about 25368.1524159723. The cubic root of 643543157 is about 863.3612628257.

The spelling of 643543157 in words is "six hundred forty-three million, five hundred forty-three thousand, one hundred fifty-seven".