643691253 has 8 divisors (see below), whose sum is σ = 903426400. Its totient is φ = 406541808.

The previous prime is 643691249. The next prime is 643691263. The reversal of 643691253 is 352196346.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 643691253 - 2² = 643691249 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (643691263) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 5646358 + ... + 5646471.

It is an arithmetic number, because the mean of its divisors is an integer number (112928300).

Almost surely, 2^643691253 is an apocalyptic number.

It is an amenable number.

643691253 is a deficient number, since it is larger than the sum of its proper divisors (259735147).

643691253 is a wasteful number, since it uses less digits than its factorization.

643691253 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 11292851.

The product of its digits is 116640, while the sum is 39.

The square root of 643691253 is about 25371.0711835350. The cubic root of 643691253 is about 863.4274850319.

The spelling of 643691253 in words is "six hundred forty-three million, six hundred ninety-one thousand, two hundred fifty-three".