51685140 has 192 divisors, whose sum is σ = 168892416. Its totient is φ = 11708928.

The previous prime is 51685129. The next prime is 51685141. The reversal of 51685140 is 4158615.

It is a Harshad number since it is a multiple of its sum of digits (30).

It is a junction number, because it is equal to n+sod(n) for n = 51685098 and 51685107.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (51685141) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 771387 + ... + 771453.

It is an arithmetic number, because the mean of its divisors is an integer number (879648).

Almost surely, 2^51685140 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 51685140, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (84446208).

51685140 is an abundant number, since it is smaller than the sum of its proper divisors (117207276).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

51685140 is a wasteful number, since it uses less digits than its factorization.

51685140 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 158 (or 156 counting only the distinct ones).

The product of its (nonzero) digits is 4800, while the sum is 30.

The square root of 51685140 is about 7189.2377899190. The cubic root of 51685140 is about 372.4962448760.

The spelling of 51685140 in words is "fifty-one million, six hundred eighty-five thousand, one hundred forty".