646451 has 4 divisors (see below), whose sum is σ = 696192. Its totient is φ = 596712.

The previous prime is 646433. The next prime is 646453. The reversal of 646451 is 154646.

It is a happy number.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 154646 = 2 ⋅77323.

It is a cyclic number.

It is not a de Polignac number, because 646451 - 2¹⁴ = 630067 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 646451.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 646451.

It is not an unprimeable number, because it can be changed into a prime (646453) 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, 24851 + ... + 24876.

It is an arithmetic number, because the mean of its divisors is an integer number (174048).

2⁶⁴⁶⁴⁵¹ is an apocalyptic number.

646451 is a deficient number, since it is larger than the sum of its proper divisors (49741).

646451 is a wasteful number, since it uses less digits than its factorization.

646451 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 49740.

The product of its digits is 2880, while the sum is 26.

The square root of 646451 is about 804.0217658745. The cubic root of 646451 is about 86.4659672103.

It can be divided in two parts, 64645 and 1, that added together give a palindrome (64646).

The spelling of 646451 in words is "six hundred forty-six thousand, four hundred fifty-one".