643540051 has 32 divisors (see below), whose sum is σ = 852664320. Its totient is φ = 470512800.

The previous prime is 643540031. The next prime is 643540061. The reversal of 643540051 is 150045346.

643540051 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a cyclic number.

It is not a de Polignac number, because 643540051 - 2²⁹ = 106669139 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (643540031) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 154486 + ... + 158596.

It is an arithmetic number, because the mean of its divisors is an integer number (26645760).

Almost surely, 2^643540051 is an apocalyptic number.

643540051 is a deficient number, since it is larger than the sum of its proper divisors (209124269).

643540051 is a wasteful number, since it uses less digits than its factorization.

643540051 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4255.

The product of its (nonzero) digits is 7200, while the sum is 28.

The square root of 643540051 is about 25368.0911974078. The cubic root of 643540051 is about 863.3598738464.

Adding to 643540051 its reverse (150045346), we get a palindrome (793585397).

The spelling of 643540051 in words is "six hundred forty-three million, five hundred forty thousand, fifty-one".