1720605657 has 16 divisors (see below), whose sum is σ = 2364468480. Its totient is φ = 1112355072.

The previous prime is 1720605647. The next prime is 1720605659. The reversal of 1720605657 is 7565060271.

It is not a de Polignac number, because 1720605657 - 2¹⁶ = 1720540121 is a prime.

It is not an unprimeable number, because it can be changed into a prime (1720605659) 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, 40608 + ... + 71345.

It is an arithmetic number, because the mean of its divisors is an integer number (147779280).

Almost surely, 2^1720605657 is an apocalyptic number.

It is an amenable number.

1720605657 is a deficient number, since it is larger than the sum of its proper divisors (643862823).

1720605657 is a wasteful number, since it uses less digits than its factorization.

1720605657 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 112112.

The product of its (nonzero) digits is 88200, while the sum is 39.

The square root of 1720605657 is about 41480.1839074997. The cubic root of 1720605657 is about 1198.2858992424.

The spelling of 1720605657 in words is "one billion, seven hundred twenty million, six hundred five thousand, six hundred fifty-seven".