643805051 has 4 divisors (see below), whose sum is σ = 644599704. Its totient is φ = 643010400.

The previous prime is 643805047. The next prime is 643805053. The reversal of 643805051 is 150508346.

It is a happy number.

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

It is a cyclic number.

It is not a de Polignac number, because 643805051 - 2² = 643805047 is a prime.

It is a super-2 number, since 2×643805051² = 828969887386225202, which contains 22 as substring.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 643804999 and 643805017.

It is not an unprimeable number, because it can be changed into a prime (643805053) 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, 396110 + ... + 397731.

It is an arithmetic number, because the mean of its divisors is an integer number (161149926).

Almost surely, 2^643805051 is an apocalyptic number.

643805051 is a deficient number, since it is larger than the sum of its proper divisors (794653).

643805051 is an equidigital number, since it uses as much as digits as its factorization.

643805051 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 794652.

The product of its (nonzero) digits is 14400, while the sum is 32.

The square root of 643805051 is about 25373.3137567800. The cubic root of 643805051 is about 863.4783637364.

The spelling of 643805051 in words is "six hundred forty-three million, eight hundred five thousand, fifty-one".