643825509 has 4 divisors (see below), whose sum is σ = 858434016. Its totient is φ = 429217004.

The previous prime is 643825459. The next prime is 643825517. The reversal of 643825509 is 905528346.

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 a cyclic number.

It is not a de Polignac number, because 643825509 - 2¹⁶ = 643759973 is a prime.

It is a super-2 number, since 2×643825509² = 829022572078218162, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (643825519) 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, 107304249 + ... + 107304254.

It is an arithmetic number, because the mean of its divisors is an integer number (214608504).

Almost surely, 2^643825509 is an apocalyptic number.

It is an amenable number.

643825509 is a deficient number, since it is larger than the sum of its proper divisors (214608507).

643825509 is a wasteful number, since it uses less digits than its factorization.

643825509 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 214608506.

The product of its (nonzero) digits is 259200, while the sum is 42.

The square root of 643825509 is about 25373.7168936677. The cubic root of 643825509 is about 863.4875098039.

The spelling of 643825509 in words is "six hundred forty-three million, eight hundred twenty-five thousand, five hundred nine".