2171561643 has 10 divisors (see below), whose sum is σ = 3243937884. Its totient is φ = 1447707708.

The previous prime is 2171561627. The next prime is 2171561647. The reversal of 2171561643 is 3461651712.

2171561643 is a `hidden beast` number, since 2 + 1 + 7 + 1 + 5 + 6 + 1 + 643 = 666.

It is not a de Polignac number, because 2171561643 - 2⁴ = 2171561627 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 2171561598 and 2171561607.

It is not an unprimeable number, because it can be changed into a prime (2171561647) 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 9 ways as a sum of consecutive naturals, for example, 13404621 + ... + 13404782.

Almost surely, 2^2171561643 is an apocalyptic number.

2171561643 is a deficient number, since it is larger than the sum of its proper divisors (1072376241).

2171561643 is an equidigital number, since it uses as much as digits as its factorization.

2171561643 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 26809415 (or 26809406 counting only the distinct ones).

The product of its digits is 30240, while the sum is 36.

The square root of 2171561643 is about 46600.0176287520. The cubic root of 2171561643 is about 1294.9630819865.

The spelling of 2171561643 in words is "two billion, one hundred seventy-one million, five hundred sixty-one thousand, six hundred forty-three".