19566694161 has 27 divisors (see below), whose sum is σ = 32882307003. Its totient is φ = 11179289520.

The previous prime is 19566694151. The next prime is 19566694183. The reversal of 19566694161 is 16149666591.

The square root of 19566694161 is 139881.

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., 18409333761 + 1157360400 = 135681^2 + 34020^2 .

It is not a de Polignac number, because 19566694161 - 2⁹ = 19566693649 is a prime.

It is a super-2 number, since 2×19566694161² (a number of 21 digits) contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 19566694098 and 19566694107.

It is not an unprimeable number, because it can be changed into a prime (19566694151) 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 26 ways as a sum of consecutive naturals, for example, 2934171 + ... + 2940831.

Almost surely, 2^19566694161 is an apocalyptic number.

19566694161 is the 139881-st square number.

19566694161 is the 69941-st centered octagonal number.

It is an amenable number.

19566694161 is a deficient number, since it is larger than the sum of its proper divisors (13315612842).

19566694161 is an frugal number, since it uses more digits than its factorization.

19566694161 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 13342 (or 6671 counting only the distinct ones).

The product of its digits is 2099520, while the sum is 54.

The spelling of 19566694161 in words is "nineteen billion, five hundred sixty-six million, six hundred ninety-four thousand, one hundred sixty-one".