17985121723 has 4 divisors (see below), whose sum is σ = 17997726600. Its totient is φ = 17972516848.

The previous prime is 17985121717. The next prime is 17985121793. The reversal of 17985121723 is 32712158971.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 32712158971 = 137 ⋅238774883.

It is a cyclic number.

It is not a de Polignac number, because 17985121723 - 2²¹ = 17983024571 is a prime.

It is a super-2 number, since 2×17985121723² (a number of 21 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (17985121793) 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, 6300298 + ... + 6303151.

It is an arithmetic number, because the mean of its divisors is an integer number (4499431650).

Almost surely, 2^17985121723 is an apocalyptic number.

17985121723 is a deficient number, since it is larger than the sum of its proper divisors (12604877).

17985121723 is a wasteful number, since it uses less digits than its factorization.

17985121723 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 12604876.

The product of its digits is 211680, while the sum is 46.

The spelling of 17985121723 in words is "seventeen billion, nine hundred eighty-five million, one hundred twenty-one thousand, seven hundred twenty-three".