643898553 has 4 divisors (see below), whose sum is σ = 858531408. Its totient is φ = 429265700.

The previous prime is 643898539. The next prime is 643898587. The reversal of 643898553 is 355898346.

It is a happy number.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-643898553 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 643898496 and 643898505.

It is not an unprimeable number, because it can be changed into a prime (643893553) 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, 107316423 + ... + 107316428.

It is an arithmetic number, because the mean of its divisors is an integer number (214632852).

Almost surely, 2^643898553 is an apocalyptic number.

It is an amenable number.

643898553 is a deficient number, since it is larger than the sum of its proper divisors (214632855).

643898553 is a wasteful number, since it uses less digits than its factorization.

643898553 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 214632854.

The product of its digits is 3110400, while the sum is 51.

The square root of 643898553 is about 25375.1562162679. The cubic root of 643898553 is about 863.5201636807.

The spelling of 643898553 in words is "six hundred forty-three million, eight hundred ninety-eight thousand, five hundred fifty-three".