51721725397 has 2 divisors, whose sum is σ = 51721725398. Its totient is φ = 51721725396.

The previous prime is 51721725379. The next prime is 51721725457. The reversal of 51721725397 is 79352712715.

Together with previous prime (51721725379) it forms an Ormiston pair, because they use the same digits, order apart.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 51637563121 + 84162276 = 227239^2 + 9174^2 .

It is a cyclic number.

It is not a de Polignac number, because 51721725397 - 2¹¹ = 51721723349 is a prime.

It is a super-3 number, since 3×51721725397³ (a number of 33 digits) contains 333 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 51721725397.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (51721723397) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 25860862698 + 25860862699.

It is an arithmetic number, because the mean of its divisors is an integer number (25860862699).

Almost surely, 2^51721725397 is an apocalyptic number.

It is an amenable number.

51721725397 is a deficient number, since it is larger than the sum of its proper divisors (1).

51721725397 is an equidigital number, since it uses as much as digits as its factorization.

51721725397 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 926100, while the sum is 49.

The spelling of 51721725397 in words is "fifty-one billion, seven hundred twenty-one million, seven hundred twenty-five thousand, three hundred ninety-seven".