1666722291 has 16 divisors (see below), whose sum is σ = 2407582464. Its totient is φ = 1019529504.

The previous prime is 1666722289. The next prime is 1666722353. The reversal of 1666722291 is 1922276661.

1666722291 is digitally balanced in base 4, because in such base it contains all the possibile digits an equal number of times.

It is not a de Polignac number, because 1666722291 - 2¹ = 1666722289 is a prime.

It is not an unprimeable number, because it can be changed into a prime (1666722221) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 121441 + ... + 134466.

It is an arithmetic number, because the mean of its divisors is an integer number (150473904).

Almost surely, 2^1666722291 is an apocalyptic number.

1666722291 is a deficient number, since it is larger than the sum of its proper divisors (740860173).

1666722291 is a wasteful number, since it uses less digits than its factorization.

1666722291 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 256090.

The product of its digits is 108864, while the sum is 42.

The square root of 1666722291 is about 40825.5102968720. The cubic root of 1666722291 is about 1185.6442913379.

The spelling of 1666722291 in words is "one billion, six hundred sixty-six million, seven hundred twenty-two thousand, two hundred ninety-one".