51781636 has 12 divisors (see below), whose sum is σ = 92328012. Its totient is φ = 25402208.

The previous prime is 51781621. The next prime is 51781673. The reversal of 51781636 is 63618715.

It can be written as a sum of positive squares in 2 ways, for example, as 19360000 + 32421636 = 4400^2 + 5694^2 .

It is a junction number, because it is equal to n+sod(n) for n = 51781595 and 51781604.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 121915 + ... + 122338.

It is an arithmetic number, because the mean of its divisors is an integer number (7694001).

Almost surely, 2^51781636 is an apocalyptic number.

It is an amenable number.

51781636 is a deficient number, since it is larger than the sum of its proper divisors (40546376).

51781636 is a wasteful number, since it uses less digits than its factorization.

51781636 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 244310 (or 244308 counting only the distinct ones).

The product of its digits is 30240, while the sum is 37.

The square root of 51781636 is about 7195.9458030199. The cubic root of 51781636 is about 372.7279172127.

The spelling of 51781636 in words is "fifty-one million, seven hundred eighty-one thousand, six hundred thirty-six".