1643925667205 has 4 divisors (see below), whose sum is σ = 1972710800652. Its totient is φ = 1315140533760.

The previous prime is 1643925667193. The next prime is 1643925667211. The reversal of 1643925667205 is 5027665293461.

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 321660256801 + 1322265410404 = 567151^2 + 1149898^2 .

It is not a de Polignac number, because 1643925667205 - 2⁶ = 1643925667141 is a prime.

It is a Duffinian number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 164392566716 + ... + 164392566725.

It is an arithmetic number, because the mean of its divisors is an integer number (493177700163).

Almost surely, 2^{1643925667205} is an apocalyptic number.

It is an amenable number.

1643925667205 is a deficient number, since it is larger than the sum of its proper divisors (328785133447).

1643925667205 is an equidigital number, since it uses as much as digits as its factorization.

1643925667205 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 328785133446.

The product of its (nonzero) digits is 16329600, while the sum is 56.

The spelling of 1643925667205 in words is "one trillion, six hundred forty-three billion, nine hundred twenty-five million, six hundred sixty-seven thousand, two hundred five".