2171661643 has 4 divisors (see below), whose sum is σ = 2171863368. Its totient is φ = 2171459920.

The previous prime is 2171661629. The next prime is 2171661659. The reversal of 2171661643 is 3461661712.

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

It is a cyclic number.

It is not a de Polignac number, because 2171661643 - 2²⁵ = 2138107211 is a prime.

It is a super-2 number, since 2×2171661643² = 9432228583354918898, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (2171661623) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 83746 + ... + 106567.

It is an arithmetic number, because the mean of its divisors is an integer number (542965842).

Almost surely, 2^2171661643 is an apocalyptic number.

2171661643 is a deficient number, since it is larger than the sum of its proper divisors (201725).

2171661643 is a wasteful number, since it uses less digits than its factorization.

2171661643 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 201724.

The product of its digits is 36288, while the sum is 37.

The square root of 2171661643 is about 46601.0905773674. The cubic root of 2171661643 is about 1294.9829592824.

The spelling of 2171661643 in words is "two billion, one hundred seventy-one million, six hundred sixty-one thousand, six hundred forty-three".