1643041591 has 4 divisors (see below), whose sum is σ = 1643853400. Its totient is φ = 1642229784.

The previous prime is 1643041579. The next prime is 1643041643. The reversal of 1643041591 is 1951403461.

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

It is a cyclic number.

It is not a de Polignac number, because 1643041591 - 2⁵ = 1643041559 is a prime.

It is a super-2 number, since 2×1643041591² = 5399171339511622562, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1643041531) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 402861 + ... + 406918.

It is an arithmetic number, because the mean of its divisors is an integer number (410963350).

Almost surely, 2^1643041591 is an apocalyptic number.

1643041591 is a deficient number, since it is larger than the sum of its proper divisors (811809).

1643041591 is an equidigital number, since it uses as much as digits as its factorization.

1643041591 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 811808.

The product of its (nonzero) digits is 12960, while the sum is 34.

The square root of 1643041591 is about 40534.4494350176. The cubic root of 1643041591 is about 1180.0022960312.

The spelling of 1643041591 in words is "one billion, six hundred forty-three million, forty-one thousand, five hundred ninety-one".