549390781681 has 27 divisors (see below), whose sum is σ = 674614781451. Its totient is φ = 446041787184.

The previous prime is 549390781679. The next prime is 549390781699. The reversal of 549390781681 is 186187093945.

The square root of 549390781681 is 741209.

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., 23597568225 + 525793213456 = 153615^2 + 725116^2 .

It is not a de Polignac number, because 549390781681 - 2¹ = 549390781679 is a prime.

It is a super-2 number, since 2×549390781681² (a number of 24 digits) contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (549390581681) 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, 98578011 + ... + 98583583.

Almost surely, 2^549390781681 is an apocalyptic number.

549390781681 is the 741209-th square number.

549390781681 is the 370605-th centered octagonal number.

It is an amenable number.

549390781681 is a deficient number, since it is larger than the sum of its proper divisors (125223999770).

549390781681 is an frugal number, since it uses more digits than its factorization.

549390781681 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 11198 (or 5599 counting only the distinct ones).

The product of its (nonzero) digits is 13063680, while the sum is 61.

The spelling of 549390781681 in words is "five hundred forty-nine billion, three hundred ninety million, seven hundred eighty-one thousand, six hundred eighty-one".