643545121 has 2 divisors, whose sum is σ = 643545122. Its totient is φ = 643545120.

The previous prime is 643545101. The next prime is 643545127. The reversal of 643545121 is 121545346.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 570254400 + 73290721 = 23880^2 + 8561^2 .

It is a cyclic number.

It is not a de Polignac number, because 643545121 - 2⁹ = 643544609 is a prime.

It is not a weakly prime, because it can be changed into another prime (643545127) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 321772560 + 321772561.

It is an arithmetic number, because the mean of its divisors is an integer number (321772561).

Almost surely, 2^643545121 is an apocalyptic number.

It is an amenable number.

643545121 is a deficient number, since it is larger than the sum of its proper divisors (1).

643545121 is an equidigital number, since it uses as much as digits as its factorization.

643545121 is an evil number, because the sum of its binary digits is even.

The product of its digits is 14400, while the sum is 31.

The square root of 643545121 is about 25368.1911258962. The cubic root of 643545121 is about 863.3621411091.

The spelling of 643545121 in words is "six hundred forty-three million, five hundred forty-five thousand, one hundred twenty-one".