51200209721 has 4 divisors (see below), whose sum is σ = 51327891444. Its totient is φ = 51072528000.

The previous prime is 51200209691. The next prime is 51200209769. The reversal of 51200209721 is 12790200215.

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 49756209721 + 1444000000 = 223061^2 + 38000^2 .

It is a cyclic number.

It is not a de Polignac number, because 51200209721 - 2³⁴ = 34020340537 is a prime.

It is a super-2 number, since 2×51200209721² (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 (51200203721) 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, 63840260 + ... + 63841061.

It is an arithmetic number, because the mean of its divisors is an integer number (12831972861).

Almost surely, 2^51200209721 is an apocalyptic number.

It is an amenable number.

51200209721 is a deficient number, since it is larger than the sum of its proper divisors (127681723).

51200209721 is a wasteful number, since it uses less digits than its factorization.

51200209721 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 127681722.

The product of its (nonzero) digits is 2520, while the sum is 29.

Adding to 51200209721 its reverse (12790200215), we get a palindrome (63990409936).

The spelling of 51200209721 in words is "fifty-one billion, two hundred million, two hundred nine thousand, seven hundred twenty-one".