643497121 has 2 divisors, whose sum is σ = 643497122. Its totient is φ = 643497120.

The previous prime is 643497097. The next prime is 643497139. The reversal of 643497121 is 121794346.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 439321600 + 204175521 = 20960^2 + 14289^2 .

It is a cyclic number.

It is not a de Polignac number, because 643497121 - 2²⁵ = 609942689 is a prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (643497191) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 321748560 + 321748561.

It is an arithmetic number, because the mean of its divisors is an integer number (321748561).

Almost surely, 2^643497121 is an apocalyptic number.

It is an amenable number.

643497121 is a deficient number, since it is larger than the sum of its proper divisors (1).

643497121 is an equidigital number, since it uses as much as digits as its factorization.

643497121 is an evil number, because the sum of its binary digits is even.

The product of its digits is 36288, while the sum is 37.

The square root of 643497121 is about 25367.2450415886. The cubic root of 643497121 is about 863.3406754228.

The spelling of 643497121 in words is "six hundred forty-three million, four hundred ninety-seven thousand, one hundred twenty-one".