643623553 has 16 divisors (see below), whose sum is σ = 692746560. Its totient is φ = 595800576.

The previous prime is 643623551. The next prime is 643623557. The reversal of 643623553 is 355326346.

It is a cyclic number.

It is not a de Polignac number, because 643623553 - 2¹ = 643623551 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (643623551) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 817426 + ... + 818212.

It is an arithmetic number, because the mean of its divisors is an integer number (43296660).

Almost surely, 2^643623553 is an apocalyptic number.

It is an amenable number.

643623553 is a deficient number, since it is larger than the sum of its proper divisors (49123007).

643623553 is a wasteful number, since it uses less digits than its factorization.

643623553 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1536.

The product of its digits is 194400, while the sum is 37.

The square root of 643623553 is about 25369.7369517305. The cubic root of 643623553 is about 863.3972137437.

Adding to 643623553 its reverse (355326346), we get a palindrome (998949899).

The spelling of 643623553 in words is "six hundred forty-three million, six hundred twenty-three thousand, five hundred fifty-three".