3919730788561 has 9 divisors (see below), whose sum is σ = 4559702957211. Its totient is φ = 3359757368352.

The previous prime is 3919730788529. The next prime is 3919730788577. The reversal of 3919730788561 is 1658870379193.

It is a happy number.

The square root of 3919730788561 is 1979831.

It is a perfect power (a square), and thus also a powerful number.

It can be written as a sum of positive squares in only one way, i.e., 891239843025 + 3028490945536 = 944055^2 + 1740256^2 .

It is not a de Polignac number, because 3919730788561 - 2⁵ = 3919730788529 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (3919730788511) by changing a digit.

It is a polite number, since it can be written in 8 ways as a sum of consecutive naturals, for example, 13717401 + ... + 14000233.

Almost surely, 2^{3919730788561} is an apocalyptic number.

3919730788561 is the 1979831-st square number.

3919730788561 is the 989916-th centered octagonal number.

It is an amenable number.

3919730788561 is a deficient number, since it is larger than the sum of its proper divisors (639972168650).

3919730788561 is an frugal number, since it uses more digits than its factorization.

3919730788561 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 565680 (or 282840 counting only the distinct ones).

The product of its (nonzero) digits is 68584320, while the sum is 67.

The spelling of 3919730788561 in words is "three trillion, nine hundred nineteen billion, seven hundred thirty million, seven hundred eighty-eight thousand, five hundred sixty-one".