538816189681 has 27 divisors (see below), whose sum is σ = 689019069963. Its totient is φ = 419812728720.

The previous prime is 538816189621. The next prime is 538816189727. The reversal of 538816189681 is 186981618835.

It is a happy number.

The square root of 538816189681 is 734041.

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., 90875117025 + 447941072656 = 301455^2 + 669284^2 .

It is not a de Polignac number, because 538816189681 - 2¹⁹ = 538815665393 is a prime.

It is a super-2 number, since 2×538816189681² (a number of 24 digits) contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (538816189601) 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, 56516391 + ... + 56525923.

Almost surely, 2^538816189681 is an apocalyptic number.

538816189681 is the 734041-st square number.

538816189681 is the 367021-st centered octagonal number.

It is an amenable number.

538816189681 is a deficient number, since it is larger than the sum of its proper divisors (150202880282).

538816189681 is an frugal number, since it uses more digits than its factorization.

538816189681 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 19102 (or 9551 counting only the distinct ones).

The product of its digits is 19906560, while the sum is 64.

Multiplying 538816189681 by its sum of digits (64), we get a square (34484236139584 = 5872328²).

The spelling of 538816189681 in words is "five hundred thirty-eight billion, eight hundred sixteen million, one hundred eighty-nine thousand, six hundred eighty-one".