643406531 has 16 divisors (see below), whose sum is σ = 714567744. Its totient is φ = 576221184.

The previous prime is 643406527. The next prime is 643406537. The reversal of 643406531 is 135604346.

643406531 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 643406531 - 2² = 643406527 is a prime.

It is a super-2 number, since 2×643406531² = 827943928266907922, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (643406537) 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, 72851 + ... + 81203.

It is an arithmetic number, because the mean of its divisors is an integer number (44660484).

Almost surely, 2^643406531 is an apocalyptic number.

643406531 is a deficient number, since it is larger than the sum of its proper divisors (71161213).

643406531 is a wasteful number, since it uses less digits than its factorization.

643406531 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 8590.

The product of its (nonzero) digits is 25920, while the sum is 32.

The square root of 643406531 is about 25365.4594084160. The cubic root of 643406531 is about 863.3001605033.

The spelling of 643406531 in words is "six hundred forty-three million, four hundred six thousand, five hundred thirty-one".