1643261265 has 48 divisors (see below), whose sum is σ = 3007368000. Its totient is φ = 827750016.

The previous prime is 1643261233. The next prime is 1643261267. The reversal of 1643261265 is 5621623461.

1643261265 is a `hidden beast` number, since 1 + 6 + 4 + 32 + 612 + 6 + 5 = 666.

It is not a de Polignac number, because 1643261265 - 2⁵ = 1643261233 is a prime.

It is not an unprimeable number, because it can be changed into a prime (1643261267) by changing a digit.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 295642 + ... + 301148.

It is an arithmetic number, because the mean of its divisors is an integer number (62653500).

Almost surely, 2^1643261265 is an apocalyptic number.

1643261265 is a gapful number since it is divisible by the number (15) formed by its first and last digit.

It is an amenable number.

1643261265 is a deficient number, since it is larger than the sum of its proper divisors (1364106735).

1643261265 is a wasteful number, since it uses less digits than its factorization.

1643261265 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5886 (or 5883 counting only the distinct ones).

The product of its digits is 51840, while the sum is 36.

The square root of 1643261265 is about 40537.1590642462. The cubic root of 1643261265 is about 1180.0548822985.

The spelling of 1643261265 in words is "one billion, six hundred forty-three million, two hundred sixty-one thousand, two hundred sixty-five".