16169919921 has 45 divisors (see below), whose sum is σ = 24623804073. Its totient is φ = 10574708760.

The previous prime is 16169919911. The next prime is 16169919947. The reversal of 16169919921 is 12991996161.

It is a happy number.

The square root of 16169919921 is 127161.

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

16169919921 is a `hidden beast` number, since 1 + 616 + 9 + 9 + 19 + 9 + 2 + 1 = 666.

It is not a de Polignac number, because 16169919921 - 2¹¹ = 16169917873 is a prime.

It is a super-2 number, since 2×16169919921² (a number of 21 digits) contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (16169919911) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 44 ways as a sum of consecutive naturals, for example, 81255780 + ... + 81255978.

Almost surely, 2^16169919921 is an apocalyptic number.

16169919921 is the 127161-st square number.

16169919921 is the 63581-st centered octagonal number.

It is an amenable number.

16169919921 is a deficient number, since it is larger than the sum of its proper divisors (8453884152).

16169919921 is an frugal number, since it uses more digits than its factorization.

16169919921 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 552 (or 273 counting only the distinct ones).

The product of its digits is 472392, while the sum is 54.

The spelling of 16169919921 in words is "sixteen billion, one hundred sixty-nine million, nine hundred nineteen thousand, nine hundred twenty-one".