51193920181 has 16 divisors (see below), whose sum is σ = 52060261680. Its totient is φ = 50335580160.

The previous prime is 51193920179. The next prime is 51193920203. The reversal of 51193920181 is 18102939115.

51193920181 = 159990² + 159991².

It can be written as a sum of positive squares in 8 ways, for example, as 25596800100 + 25597120081 = 159990^2 + 159991^2 .

It is a cyclic number.

It is not a de Polignac number, because 51193920181 - 2¹ = 51193920179 is a prime.

It is a super-2 number, since 2×51193920181² (a number of 22 digits) contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (51193924181) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 10193451 + ... + 10198471.

It is an arithmetic number, because the mean of its divisors is an integer number (3253766355).

Almost surely, 2^51193920181 is an apocalyptic number.

51193920181 is the 159991-st centered square number.

It is an amenable number.

51193920181 is a deficient number, since it is larger than the sum of its proper divisors (866341499).

51193920181 is a wasteful number, since it uses less digits than its factorization.

With its predecessor (51193920180) it forms a Ruth-Aaron pair, since the sum of their distinct prime factors is the same (5784).

51193920181 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5784.

The product of its (nonzero) digits is 19440, while the sum is 40.

The spelling of 51193920181 in words is "fifty-one billion, one hundred ninety-three million, nine hundred twenty thousand, one hundred eighty-one".