1641165591 has 24 divisors (see below), whose sum is σ = 2375249520. Its totient is φ = 1007924112.

The previous prime is 1641165583. The next prime is 1641165611. The reversal of 1641165591 is 1955611461.

It is not a de Polignac number, because 1641165591 - 2³ = 1641165583 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (39).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1641165521) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 3288660 + ... + 3289158.

It is an arithmetic number, because the mean of its divisors is an integer number (98968730).

Almost surely, 2^1641165591 is an apocalyptic number.

1641165591 is a deficient number, since it is larger than the sum of its proper divisors (734083929).

1641165591 is an frugal number, since it uses more digits than its factorization.

1641165591 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1040 (or 515 counting only the distinct ones).

The product of its digits is 32400, while the sum is 39.

The square root of 1641165591 is about 40511.3020156104. The cubic root of 1641165591 is about 1179.5530220807.

Multiplying 1641165591 by its sum of digits (39), we get a square (64005458049 = 252993²).

1641165591 divided by its sum of digits (39) gives a square (42081169 = 6487²).

The spelling of 1641165591 in words is "one billion, six hundred forty-one million, one hundred sixty-five thousand, five hundred ninety-one".