643616453 has 4 divisors (see below), whose sum is σ = 644567820. Its totient is φ = 642665088.

The previous prime is 643616423. The next prime is 643616461. The reversal of 643616453 is 354616346.

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

It can be written as a sum of positive squares in 2 ways, for example, as 642216964 + 1399489 = 25342^2 + 1183^2 .

It is a cyclic number.

It is not a de Polignac number, because 643616453 - 2²⁸ = 375180997 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (643616423) 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, 474668 + ... + 476021.

It is an arithmetic number, because the mean of its divisors is an integer number (161141955).

Almost surely, 2^643616453 is an apocalyptic number.

It is an amenable number.

643616453 is a deficient number, since it is larger than the sum of its proper divisors (951367).

643616453 is an equidigital number, since it uses as much as digits as its factorization.

643616453 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 951366.

The product of its digits is 155520, while the sum is 38.

The square root of 643616453 is about 25369.5970208437. The cubic root of 643616453 is about 863.3940389362.

The spelling of 643616453 in words is "six hundred forty-three million, six hundred sixteen thousand, four hundred fifty-three".