51121085621 has 4 divisors (see below), whose sum is σ = 51131765100. Its totient is φ = 51110406144.

The previous prime is 51121085593. The next prime is 51121085623. The reversal of 51121085621 is 12658012115.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 28963274596 + 22157811025 = 170186^2 + 148855^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-51121085621 is a prime.

It is a super-2 number, since 2×51121085621² (a number of 22 digits) contains 22 as substring.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (51121085623) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 5332556 + ... + 5342133.

It is an arithmetic number, because the mean of its divisors is an integer number (12782941275).

Almost surely, 2^51121085621 is an apocalyptic number.

It is an amenable number.

51121085621 is a deficient number, since it is larger than the sum of its proper divisors (10679479).

51121085621 is a wasteful number, since it uses less digits than its factorization.

51121085621 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10679478.

The product of its (nonzero) digits is 4800, while the sum is 32.

Adding to 51121085621 its reverse (12658012115), we get a palindrome (63779097736).

The spelling of 51121085621 in words is "fifty-one billion, one hundred twenty-one million, eighty-five thousand, six hundred twenty-one".