1721665105 has 8 divisors (see below), whose sum is σ = 2069225064. Its totient is φ = 1375180800.

The previous prime is 1721665103. The next prime is 1721665109. The reversal of 1721665105 is 5015661271.

It can be written as a sum of positive squares in 4 ways, for example, as 293505424 + 1428159681 = 17132^2 + 37791^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 1721665105 - 2¹ = 1721665103 is a prime.

It is a super-2 number, since 2×1721665105² = 5928261467549322050, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1721665103) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 265386 + ... + 271795.

It is an arithmetic number, because the mean of its divisors is an integer number (258653133).

Almost surely, 2^1721665105 is an apocalyptic number.

It is an amenable number.

1721665105 is a deficient number, since it is larger than the sum of its proper divisors (347559959).

1721665105 is an equidigital number, since it uses as much as digits as its factorization.

1721665105 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 537827.

The product of its (nonzero) digits is 12600, while the sum is 34.

The square root of 1721665105 is about 41492.9524738840. The cubic root of 1721665105 is about 1198.5317934944.

The spelling of 1721665105 in words is "one billion, seven hundred twenty-one million, six hundred sixty-five thousand, one hundred five".