21161154665545 has 16 divisors (see below), whose sum is σ = 25809986836368. Its totient is φ = 16651196375040.

The previous prime is 21161154665531. The next prime is 21161154665587. The reversal of 21161154665545 is 54556645116112.

It can be written as a sum of positive squares in 8 ways, for example, as 2032244122624 + 19128910542921 = 1425568^2 + 4373661^2 .

It is not a de Polignac number, because 21161154665545 - 2²⁵ = 21161121111113 is a prime.

It is a super-3 number, since 3×21161154665545³ (a number of 41 digits) contains 333 as substring.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21161154665492 and 21161154665501.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 27515077 + ... + 28273693.

It is an arithmetic number, because the mean of its divisors is an integer number (1613124177273).

Almost surely, 2^{21161154665545} is an apocalyptic number.

It is an amenable number.

21161154665545 is a deficient number, since it is larger than the sum of its proper divisors (4648832170823).

21161154665545 is an equidigital number, since it uses as much as digits as its factorization.

21161154665545 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 850140.

The product of its digits is 4320000, while the sum is 52.

The spelling of 21161154665545 in words is "twenty-one trillion, one hundred sixty-one billion, one hundred fifty-four million, six hundred sixty-five thousand, five hundred forty-five".