51520551491 has 2 divisors, whose sum is σ = 51520551492. Its totient is φ = 51520551490.

The previous prime is 51520551473. The next prime is 51520551557. The reversal of 51520551491 is 19415502515.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 51520551491 - 2⁶ = 51520551427 is a prime.

It is not a weakly prime, because it can be changed into another prime (51520551421) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 25760275745 + 25760275746.

It is an arithmetic number, because the mean of its divisors is an integer number (25760275746).

Almost surely, 2^51520551491 is an apocalyptic number.

51520551491 is a deficient number, since it is larger than the sum of its proper divisors (1).

51520551491 is an equidigital number, since it uses as much as digits as its factorization.

51520551491 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 45000, while the sum is 38.

The spelling of 51520551491 in words is "fifty-one billion, five hundred twenty million, five hundred fifty-one thousand, four hundred ninety-one".