5171721665 has 16 divisors (see below), whose sum is σ = 6837293376. Its totient is φ = 3724008000.

The previous prime is 5171721613. The next prime is 5171721679. The reversal of 5171721665 is 5661271715.

It is not a de Polignac number, because 5171721665 - 2⁶ = 5171721601 is a prime.

It is a Duffinian number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 459947 + ... + 471056.

It is an arithmetic number, because the mean of its divisors is an integer number (427330836).

Almost surely, 2^5171721665 is an apocalyptic number.

5171721665 is a gapful number since it is divisible by the number (55) formed by its first and last digit.

It is an amenable number.

5171721665 is a deficient number, since it is larger than the sum of its proper divisors (1665571711).

5171721665 is a wasteful number, since it uses less digits than its factorization.

5171721665 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 931120.

The product of its digits is 88200, while the sum is 41.

The square root of 5171721665 is about 71914.6832364574. The cubic root of 5171721665 is about 1729.3320134863.

The spelling of 5171721665 in words is "five billion, one hundred seventy-one million, seven hundred twenty-one thousand, six hundred sixty-five".