2165138616481 has 3 divisors (see below), whose sum is σ = 2165140087923. Its totient is φ = 2165137145040.

The previous prime is 2165138616467. The next prime is 2165138616491. The reversal of 2165138616481 is 1846168315612.

The square root of 2165138616481 is 1471441.

It is a perfect power (a square), and thus also a powerful number.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It can be written as a sum of positive squares in only one way, i.e., 64842038881 + 2100296577600 = 254641^2 + 1449240^2 .

It is not a de Polignac number, because 2165138616481 - 2⁷ = 2165138616353 is a prime.

It is a super-2 number, since 2×2165138616481² (a number of 25 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (2165138616401) by changing a digit.

It is a polite number, since it can be written in 2 ways as a sum of consecutive naturals, for example, 735721 + ... + 2207161.

It is an arithmetic number, because the mean of its divisors is an integer number (721713362641).

Almost surely, 2^{2165138616481} is an apocalyptic number.

2165138616481 is the 1471441-st square number.

2165138616481 is the 735721-st centered octagonal number.

It is an amenable number.

2165138616481 is a deficient number, since it is larger than the sum of its proper divisors (1471442).

2165138616481 is an frugal number, since it uses more digits than its factorization.

2165138616481 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2942882 (or 1471441 counting only the distinct ones).

The product of its digits is 1658880, while the sum is 52.

The spelling of 2165138616481 in words is "two trillion, one hundred sixty-five billion, one hundred thirty-eight million, six hundred sixteen thousand, four hundred eighty-one".