643523929 has 2 divisors, whose sum is σ = 643523930. Its totient is φ = 643523928.

The previous prime is 643523921. The next prime is 643523941. The reversal of 643523929 is 929325346.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 392238025 + 251285904 = 19805^2 + 15852^2 .

It is a cyclic number.

It is not a de Polignac number, because 643523929 - 2³ = 643523921 is a prime.

It is not a weakly prime, because it can be changed into another prime (643523921) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 321761964 + 321761965.

It is an arithmetic number, because the mean of its divisors is an integer number (321761965).

Almost surely, 2^643523929 is an apocalyptic number.

It is an amenable number.

643523929 is a deficient number, since it is larger than the sum of its proper divisors (1).

643523929 is an equidigital number, since it uses as much as digits as its factorization.

643523929 is an evil number, because the sum of its binary digits is even.

The product of its digits is 349920, while the sum is 43.

The square root of 643523929 is about 25367.7734340245. The cubic root of 643523929 is about 863.3526641402.

The spelling of 643523929 in words is "six hundred forty-three million, five hundred twenty-three thousand, nine hundred twenty-nine".