55205731681 has 3 divisors (see below), whose sum is σ = 55205966641. Its totient is φ = 55205496722.

The previous prime is 55205731673. The next prime is 55205731699. The reversal of 55205731681 is 18613750255.

It is a happy number.

The square root of 55205731681 is 234959.

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

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It is not a de Polignac number, because 55205731681 - 2³ = 55205731673 is a prime.

It is a super-2 number, since 2×55205731681² (a number of 22 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (55205731621) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 2 ways as a sum of consecutive naturals, for example, 117480 + ... + 352438.

Almost surely, 2^55205731681 is an apocalyptic number.

55205731681 is the 234959-th square number.

55205731681 is the 117480-th centered octagonal number.

It is an amenable number.

55205731681 is a deficient number, since it is larger than the sum of its proper divisors (234960).

55205731681 is an frugal number, since it uses more digits than its factorization.

55205731681 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 469918 (or 234959 counting only the distinct ones).

The product of its (nonzero) digits is 252000, while the sum is 43.

The spelling of 55205731681 in words is "fifty-five billion, two hundred five million, seven hundred thirty-one thousand, six hundred eighty-one".