643953 has 4 divisors (see below), whose sum is σ = 858608. Its totient is φ = 429300.

The previous prime is 643949. The next prime is 643957. The reversal of 643953 is 359346.

It is a happy number.

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 an interprime number because it is at equal distance from previous prime (643949) and next prime (643957).

It is not a de Polignac number, because 643953 - 2² = 643949 is a prime.

It is a D-number.

It is a Duffinian number.

643953 is a lucky number.

It is a self number, because there is not a number n which added to its sum of digits gives 643953.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 643953.

It is not an unprimeable number, because it can be changed into a prime (643957) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 107323 + ... + 107328.

It is an arithmetic number, because the mean of its divisors is an integer number (214652).

2⁶⁴³⁹⁵³ is an apocalyptic number.

It is an amenable number.

643953 is a deficient number, since it is larger than the sum of its proper divisors (214655).

643953 is a wasteful number, since it uses less digits than its factorization.

643953 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 214654.

The product of its digits is 9720, while the sum is 30.

The square root of 643953 is about 802.4668217441. The cubic root of 643953 is about 86.3544502275.

It can be divided in two parts, 643 and 953, that added together give a triangular number (1596 = T₅₆).

The spelling of 643953 in words is "six hundred forty-three thousand, nine hundred fifty-three".