643257849 has 32 divisors (see below), whose sum is σ = 981227520. Its totient is φ = 371331072.

The previous prime is 643257847. The next prime is 643257851. The reversal of 643257849 is 948752346.

It is an interprime number because it is at equal distance from previous prime (643257847) and next prime (643257851).

It is not a de Polignac number, because 643257849 - 2¹ = 643257847 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 643257798 and 643257807.

It is not an unprimeable number, because it can be changed into a prime (643257847) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 221992 + ... + 224870.

It is an arithmetic number, because the mean of its divisors is an integer number (30663360).

Almost surely, 2^643257849 is an apocalyptic number.

It is an amenable number.

643257849 is a deficient number, since it is larger than the sum of its proper divisors (337969671).

643257849 is a wasteful number, since it uses less digits than its factorization.

643257849 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3249.

The product of its digits is 1451520, while the sum is 48.

The square root of 643257849 is about 25362.5284425666. The cubic root of 643257849 is about 863.2336566281.

The spelling of 643257849 in words is "six hundred forty-three million, two hundred fifty-seven thousand, eight hundred forty-nine".