1721666723 has 8 divisors (see below), whose sum is σ = 2013378048. Its totient is φ = 1441395144.

The previous prime is 1721666719. The next prime is 1721666731. The reversal of 1721666723 is 3276661271.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 1721666723 - 2² = 1721666719 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1721666743) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 2859611 + ... + 2860212.

It is an arithmetic number, because the mean of its divisors is an integer number (251672256).

Almost surely, 2^1721666723 is an apocalyptic number.

1721666723 is a deficient number, since it is larger than the sum of its proper divisors (291711325).

1721666723 is an equidigital number, since it uses as much as digits as its factorization.

1721666723 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5719873.

The product of its digits is 127008, while the sum is 41.

The square root of 1721666723 is about 41492.9719711664. The cubic root of 1721666723 is about 1198.5321689495.

The spelling of 1721666723 in words is "one billion, seven hundred twenty-one million, six hundred sixty-six thousand, seven hundred twenty-three".