215165171881 has 9 divisors (see below), whose sum is σ = 236509475223. Its totient is φ = 195600063120.

The previous prime is 215165171873. The next prime is 215165171917. The reversal of 215165171881 is 188171561512.

The square root of 215165171881 is 463859.

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

It can be written as a sum of positive squares in only one way, i.e., 212236197481 + 2928974400 = 460691^2 + 54120^2 .

It is not a de Polignac number, because 215165171881 - 2³ = 215165171873 is a prime.

It is a super-2 number, since 2×215165171881² (a number of 23 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (215165171831) by changing a digit.

It is a polite number, since it can be written in 8 ways as a sum of consecutive naturals, for example, 5081365 + ... + 5123533.

Almost surely, 2^215165171881 is an apocalyptic number.

215165171881 is the 463859-th square number.

215165171881 is the 231930-th centered octagonal number.

It is an amenable number.

215165171881 is a deficient number, since it is larger than the sum of its proper divisors (21344303342).

215165171881 is an frugal number, since it uses more digits than its factorization.

215165171881 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 84360 (or 42180 counting only the distinct ones).

The product of its digits is 134400, while the sum is 46.

The spelling of 215165171881 in words is "two hundred fifteen billion, one hundred sixty-five million, one hundred seventy-one thousand, eight hundred eighty-one".