1720020561 has 16 divisors (see below), whose sum is σ = 2684911488. Its totient is φ = 958896000.

The previous prime is 1720020527. The next prime is 1720020623. The reversal of 1720020561 is 1650200271.

It is not a de Polignac number, because 1720020561 - 2⁷ = 1720020433 is a prime.

It is not an unprimeable number, because it can be changed into a prime (1720020161) 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, 997990 + ... + 999711.

It is an arithmetic number, because the mean of its divisors is an integer number (167806968).

Almost surely, 2^1720020561 is an apocalyptic number.

It is an amenable number.

1720020561 is a deficient number, since it is larger than the sum of its proper divisors (964890927).

1720020561 is a wasteful number, since it uses less digits than its factorization.

1720020561 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1997752.

The product of its (nonzero) digits is 840, while the sum is 24.

The square root of 1720020561 is about 41473.1305907813. The cubic root of 1720020561 is about 1198.1500571974.

The spelling of 1720020561 in words is "one billion, seven hundred twenty million, twenty thousand, five hundred sixty-one".