51972821787 has 64 divisors (see below), whose sum is σ = 78862947840. Its totient is φ = 30245529600.

The previous prime is 51972821737. The next prime is 51972821833. The reversal of 51972821787 is 78712827915.

It is a happy number.

It is not a de Polignac number, because 51972821787 - 2¹¹ = 51972819739 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (57).

It is not an unprimeable number, because it can be changed into a prime (51972821737) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 33946212 + ... + 33947742.

It is an arithmetic number, because the mean of its divisors is an integer number (1232233560).

Almost surely, 2^51972821787 is an apocalyptic number.

51972821787 is a gapful number since it is divisible by the number (57) formed by its first and last digit.

51972821787 is a deficient number, since it is larger than the sum of its proper divisors (26890126053).

51972821787 is a wasteful number, since it uses less digits than its factorization.

51972821787 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2284.

The product of its digits is 3951360, while the sum is 57.

The spelling of 51972821787 in words is "fifty-one billion, nine hundred seventy-two million, eight hundred twenty-one thousand, seven hundred eighty-seven".