2156555609 has 4 divisors (see below), whose sum is σ = 2322444516. Its totient is φ = 1990666704.

The previous prime is 2156555603. The next prime is 2156555617. The reversal of 2156555609 is 9065556512.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 220819600 + 1935736009 = 14860^2 + 43997^2 .

It is not a de Polignac number, because 2156555609 - 2⁴ = 2156555593 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a self number, because there is not a number n which added to its sum of digits gives 2156555609.

It is not an unprimeable number, because it can be changed into a prime (2156555603) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 82944434 + ... + 82944459.

It is an arithmetic number, because the mean of its divisors is an integer number (580611129).

Almost surely, 2^2156555609 is an apocalyptic number.

It is an amenable number.

2156555609 is a deficient number, since it is larger than the sum of its proper divisors (165888907).

2156555609 is a wasteful number, since it uses less digits than its factorization.

2156555609 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 165888906.

The product of its (nonzero) digits is 405000, while the sum is 44.

The square root of 2156555609 is about 46438.7296230205. The cubic root of 2156555609 is about 1291.9733451881.

The spelling of 2156555609 in words is "two billion, one hundred fifty-six million, five hundred fifty-five thousand, six hundred nine".