215805851091 has 48 divisors (see below), whose sum is σ = 338240448000. Its totient is φ = 132151224384.

The previous prime is 215805851071. The next prime is 215805851101. The reversal of 215805851091 is 190158508512.

It is a happy number.

215805851091 is a `hidden beast` number, since 2 + 1 + 5 + 80 + 58 + 510 + 9 + 1 = 666.

It is not a de Polignac number, because 215805851091 - 2¹⁰ = 215805850067 is a prime.

It is a super-2 number, since 2×215805851091² (a number of 23 digits) contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (215805851071) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 734485 + ... + 985433.

It is an arithmetic number, because the mean of its divisors is an integer number (7046676000).

Almost surely, 2^215805851091 is an apocalyptic number.

215805851091 is a deficient number, since it is larger than the sum of its proper divisors (122434596909).

215805851091 is a wasteful number, since it uses less digits than its factorization.

215805851091 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 251128 (or 251125 counting only the distinct ones).

The product of its (nonzero) digits is 144000, while the sum is 45.

The spelling of 215805851091 in words is "two hundred fifteen billion, eight hundred five million, eight hundred fifty-one thousand, ninety-one".