2171042721 has 6 divisors (see below), whose sum is σ = 3135950610. Its totient is φ = 1447361808.

The previous prime is 2171042719. The next prime is 2171042729. The reversal of 2171042721 is 1272401712.

It is a happy number.

2171042721 is a `hidden beast` number, since 217 + 1 + 0 + 427 + 21 = 666.

2171042721 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It can be written as a sum of positive squares in only one way, i.e., 2048829696 + 122213025 = 45264^2 + 11055^2 .

It is not a de Polignac number, because 2171042721 - 2¹ = 2171042719 is a prime.

It is not an unprimeable number, because it can be changed into a prime (2171042729) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 120613476 + ... + 120613493.

It is an arithmetic number, because the mean of its divisors is an integer number (522658435).

Almost surely, 2^2171042721 is an apocalyptic number.

It is an amenable number.

2171042721 is a deficient number, since it is larger than the sum of its proper divisors (964907889).

2171042721 is a wasteful number, since it uses less digits than its factorization.

2171042721 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 241226975 (or 241226972 counting only the distinct ones).

The product of its (nonzero) digits is 1568, while the sum is 27.

The square root of 2171042721 is about 46594.4494655748. The cubic root of 2171042721 is about 1294.8599245240.

The spelling of 2171042721 in words is "two billion, one hundred seventy-one million, forty-two thousand, seven hundred twenty-one".