10165661555521 has 4 divisors (see below), whose sum is σ = 10270462190212. Its totient is φ = 10060860920832.

The previous prime is 10165661555513. The next prime is 10165661555549. The reversal of 10165661555521 is 12555516656101.

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

It can be written as a sum of positive squares in 2 ways, for example, as 8410208801296 + 1755452754225 = 2900036^2 + 1324935^2 .

It is a cyclic number.

It is not a de Polignac number, because 10165661555521 - 2³ = 10165661555513 is a prime.

It is a super-2 number, since 2×10165661555521² (a number of 27 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (10165661555501) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 52400317200 + ... + 52400317393.

It is an arithmetic number, because the mean of its divisors is an integer number (2567615547553).

Almost surely, 2^{10165661555521} is an apocalyptic number.

It is an amenable number.

10165661555521 is a deficient number, since it is larger than the sum of its proper divisors (104800634691).

10165661555521 is an equidigital number, since it uses as much as digits as its factorization.

10165661555521 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 104800634690.

The product of its (nonzero) digits is 1350000, while the sum is 49.

The spelling of 10165661555521 in words is "ten trillion, one hundred sixty-five billion, six hundred sixty-one million, five hundred fifty-five thousand, five hundred twenty-one".