1720345657 has 4 divisors (see below), whose sum is σ = 1730647296. Its totient is φ = 1710044020.

The previous prime is 1720345639. The next prime is 1720345663. The reversal of 1720345657 is 7565430271.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 1720345657 - 2¹¹ = 1720343609 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1720345637) 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, 5150569 + ... + 5150902.

It is an arithmetic number, because the mean of its divisors is an integer number (432661824).

Almost surely, 2^1720345657 is an apocalyptic number.

It is an amenable number.

1720345657 is a deficient number, since it is larger than the sum of its proper divisors (10301639).

1720345657 is a wasteful number, since it uses less digits than its factorization.

1720345657 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10301638.

The product of its (nonzero) digits is 176400, while the sum is 40.

The square root of 1720345657 is about 41477.0497624891. The cubic root of 1720345657 is about 1198.2255387085.

The spelling of 1720345657 in words is "one billion, seven hundred twenty million, three hundred forty-five thousand, six hundred fifty-seven".