18645892611921 has 27 divisors (see below), whose sum is σ = 28155316944027. Its totient is φ = 11889944423280.

The previous prime is 18645892611911. The next prime is 18645892611943. The reversal of 18645892611921 is 12911629854681.

The square root of 18645892611921 is 4318089.

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

18645892611921 is a `hidden beast` number, since 1 + 8 + 6 + 4 + 5 + 8 + 9 + 2 + 611 + 9 + 2 + 1 = 666.

It can be written as a sum of positive squares in only one way, i.e., 18549482361921 + 96410250000 = 4306911^2 + 310500^2 .

It is not a de Polignac number, because 18645892611921 - 2¹³ = 18645892603729 is a prime.

It is a super-2 number, since 2×18645892611921² (a number of 27 digits) contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (18645892611901) by changing a digit.

It is a polite number, since it can be written in 26 ways as a sum of consecutive naturals, for example, 297916851 + ... + 297979431.

Almost surely, 2^{18645892611921} is an apocalyptic number.

18645892611921 is the 4318089-th square number.

18645892611921 is the 2159045-th centered octagonal number.

It is an amenable number.

18645892611921 is a deficient number, since it is larger than the sum of its proper divisors (9509424332106).

18645892611921 is an frugal number, since it uses more digits than its factorization.

18645892611921 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 125214 (or 62607 counting only the distinct ones).

The product of its digits is 14929920, while the sum is 63.

The spelling of 18645892611921 in words is "eighteen trillion, six hundred forty-five billion, eight hundred ninety-two million, six hundred eleven thousand, nine hundred twenty-one".