643166401 has 4 divisors (see below), whose sum is σ = 645669252. Its totient is φ = 640663552.

The previous prime is 643166369. The next prime is 643166417. The reversal of 643166401 is 104661346.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 363474225 + 279692176 = 19065^2 + 16724^2 .

It is a cyclic number.

It is not a de Polignac number, because 643166401 - 2⁵ = 643166369 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (643166441) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1251040 + ... + 1251553.

It is an arithmetic number, because the mean of its divisors is an integer number (161417313).

Almost surely, 2^643166401 is an apocalyptic number.

It is an amenable number.

643166401 is a deficient number, since it is larger than the sum of its proper divisors (2502851).

643166401 is a wasteful number, since it uses less digits than its factorization.

643166401 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2502850.

The product of its (nonzero) digits is 10368, while the sum is 31.

The square root of 643166401 is about 25360.7255613872. The cubic root of 643166401 is about 863.1927478216.

The spelling of 643166401 in words is "six hundred forty-three million, one hundred sixty-six thousand, four hundred one".