2155706217 has 32 divisors (see below), whose sum is σ = 3694959360. Its totient is φ = 1231823376.

The previous prime is 2155706197. The next prime is 2155706227. The reversal of 2155706217 is 7126075512.

2155706217 is a `hidden beast` number, since 2 + 15 + 570 + 62 + 17 = 666.

It is not a de Polignac number, because 2155706217 - 2¹¹ = 2155704169 is a prime.

It is not an unprimeable number, because it can be changed into a prime (2155706227) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 55098 + ... + 85715.

It is an arithmetic number, because the mean of its divisors is an integer number (115467480).

Almost surely, 2^2155706217 is an apocalyptic number.

2155706217 is a gapful number since it is divisible by the number (27) formed by its first and last digit.

It is an amenable number.

2155706217 is a deficient number, since it is larger than the sum of its proper divisors (1539253143).

2155706217 is an frugal number, since it uses more digits than its factorization.

2155706217 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 140841 (or 140823 counting only the distinct ones).

The product of its (nonzero) digits is 29400, while the sum is 36.

The square root of 2155706217 is about 46429.5834247950. The cubic root of 2155706217 is about 1291.8037018418.

The spelling of 2155706217 in words is "two billion, one hundred fifty-five million, seven hundred six thousand, two hundred seventeen".