2161787506 has 4 divisors (see below), whose sum is σ = 3242681262. Its totient is φ = 1080893752.

The previous prime is 2161787501. The next prime is 2161787557. The reversal of 2161787506 is 6057871612.

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

It can be written as a sum of positive squares in only one way, i.e., 2144523481 + 17264025 = 46309^2 + 4155^2 .

It is a super-3 number, since 3×2161787506³ (a number of 29 digits) contains 333 as substring.

It is not an unprimeable number, because it can be changed into a prime (2161787501) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 540446875 + ... + 540446878.

Almost surely, 2^2161787506 is an apocalyptic number.

2161787506 is a deficient number, since it is larger than the sum of its proper divisors (1080893756).

2161787506 is a wasteful number, since it uses less digits than its factorization.

2161787506 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1080893755.

The product of its (nonzero) digits is 141120, while the sum is 43.

The square root of 2161787506 is about 46495.0266802805. The cubic root of 2161787506 is about 1293.0172957884.

The spelling of 2161787506 in words is "two billion, one hundred sixty-one million, seven hundred eighty-seven thousand, five hundred six".