643960225 has 24 divisors (see below), whose sum is σ = 839644920. Its totient is φ = 489216000.

The previous prime is 643960211. The next prime is 643960267. The reversal of 643960225 is 522069346.

It can be written as a sum of positive squares in 12 ways, for example, as 204261264 + 439698961 = 14292^2 + 20969^2 .

It is not a de Polignac number, because 643960225 - 2⁵ = 643960193 is a prime.

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 36945 + ... + 51505.

It is an arithmetic number, because the mean of its divisors is an integer number (34985205).

Almost surely, 2^643960225 is an apocalyptic number.

It is an amenable number.

643960225 is a deficient number, since it is larger than the sum of its proper divisors (195684695).

643960225 is a wasteful number, since it uses less digits than its factorization.

643960225 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 14661 (or 14656 counting only the distinct ones).

The product of its (nonzero) digits is 77760, while the sum is 37.

The square root of 643960225 is about 25376.3713915130. The cubic root of 643960225 is about 863.5477318512.

The spelling of 643960225 in words is "six hundred forty-three million, nine hundred sixty thousand, two hundred twenty-five".