643136401 has 4 divisors (see below), whose sum is σ = 680967972. Its totient is φ = 605304832.

The previous prime is 643136383. The next prime is 643136407. The reversal of 643136401 is 104631346.

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 481846401 + 161290000 = 21951^2 + 12700^2 .

It is a cyclic number.

It is not a de Polignac number, because 643136401 - 2¹⁷ = 643005329 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 643136401.

It is not an unprimeable number, because it can be changed into a prime (643136407) 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, 18915760 + ... + 18915793.

It is an arithmetic number, because the mean of its divisors is an integer number (170241993).

Almost surely, 2^643136401 is an apocalyptic number.

It is an amenable number.

643136401 is a deficient number, since it is larger than the sum of its proper divisors (37831571).

643136401 is a wasteful number, since it uses less digits than its factorization.

643136401 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 37831570.

The product of its (nonzero) digits is 5184, while the sum is 28.

The square root of 643136401 is about 25360.1340887622. The cubic root of 643136401 is about 863.1793266266.

Adding to 643136401 its reverse (104631346), we get a palindrome (747767747).

The spelling of 643136401 in words is "six hundred forty-three million, one hundred thirty-six thousand, four hundred one".