1720390723 has 4 divisors (see below), whose sum is σ = 1720474720. Its totient is φ = 1720306728.

The previous prime is 1720390697. The next prime is 1720390757. The reversal of 1720390723 is 3270930271.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It is a cyclic number.

It is not a de Polignac number, because 1720390723 - 2²¹ = 1718293571 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1720340723) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 11113 + ... + 59701.

It is an arithmetic number, because the mean of its divisors is an integer number (430118680).

Almost surely, 2^1720390723 is an apocalyptic number.

1720390723 is a deficient number, since it is larger than the sum of its proper divisors (83997).

1720390723 is an equidigital number, since it uses as much as digits as its factorization.

1720390723 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 83996.

The product of its (nonzero) digits is 15876, while the sum is 34.

The square root of 1720390723 is about 41477.5930232216. The cubic root of 1720390723 is about 1198.2360014820.

The spelling of 1720390723 in words is "one billion, seven hundred twenty million, three hundred ninety thousand, seven hundred twenty-three".