643236513 has 4 divisors (see below), whose sum is σ = 857648688. Its totient is φ = 428824340.

The previous prime is 643236493. The next prime is 643236523. The reversal of 643236513 is 315632346.

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 643236513 - 2¹⁸ = 642974369 is a prime.

It is not an unprimeable number, because it can be changed into a prime (643236523) 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, 107206083 + ... + 107206088.

It is an arithmetic number, because the mean of its divisors is an integer number (214412172).

Almost surely, 2^643236513 is an apocalyptic number.

It is an amenable number.

643236513 is a deficient number, since it is larger than the sum of its proper divisors (214412175).

643236513 is a wasteful number, since it uses less digits than its factorization.

643236513 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 214412174.

The product of its digits is 38880, while the sum is 33.

The square root of 643236513 is about 25362.1078185548. The cubic root of 643236513 is about 863.2241124217.

Adding to 643236513 its reverse (315632346), we get a palindrome (958868859).

The spelling of 643236513 in words is "six hundred forty-three million, two hundred thirty-six thousand, five hundred thirteen".