51720491787 has 16 divisors (see below), whose sum is σ = 69152305152. Its totient is φ = 34384633920.

The previous prime is 51720491783. The next prime is 51720491789. The reversal of 51720491787 is 78719402715.

It is not a de Polignac number, because 51720491787 - 2² = 51720491783 is a prime.

It is not an unprimeable number, because it can be changed into a prime (51720491783) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 1643343 + ... + 1674519.

It is an arithmetic number, because the mean of its divisors is an integer number (4322019072).

Almost surely, 2^51720491787 is an apocalyptic number.

51720491787 is a deficient number, since it is larger than the sum of its proper divisors (17431813365).

51720491787 is a wasteful number, since it uses less digits than its factorization.

51720491787 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 32698.

The product of its (nonzero) digits is 987840, while the sum is 51.

The spelling of 51720491787 in words is "fifty-one billion, seven hundred twenty million, four hundred ninety-one thousand, seven hundred eighty-seven".