643451 has 4 divisors (see below), whose sum is σ = 647472. Its totient is φ = 639432.

The previous prime is 643439. The next prime is 643453. The reversal of 643451 is 154346.

It is a happy number.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 643451 - 2¹⁰ = 642427 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (643453) 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, 1760 + ... + 2093.

It is an arithmetic number, because the mean of its divisors is an integer number (161868).

2⁶⁴³⁴⁵¹ is an apocalyptic number.

643451 is a deficient number, since it is larger than the sum of its proper divisors (4021).

643451 is a wasteful number, since it uses less digits than its factorization.

643451 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4020.

The product of its digits is 1440, while the sum is 23.

The square root of 643451 is about 802.1539752442. The cubic root of 643451 is about 86.3320049023.

Adding to 643451 its reverse (154346), we get a palindrome (797797).

It can be divided in two parts, 64345 and 1, that added together give a palindrome (64346).

The spelling of 643451 in words is "six hundred forty-three thousand, four hundred fifty-one".