51381918 has 64 divisors (see below), whose sum is σ = 131389440. Its totient is φ = 14580000.

The previous prime is 51381917. The next prime is 51381929. The reversal of 51381918 is 81918315.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (51381917) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 68043 + ... + 68793.

It is an arithmetic number, because the mean of its divisors is an integer number (2052960).

Almost surely, 2^51381918 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 51381918, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (65694720).

51381918 is an abundant number, since it is smaller than the sum of its proper divisors (80007522).

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

51381918 is a wasteful number, since it uses less digits than its factorization.

51381918 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 950 (or 944 counting only the distinct ones).

The product of its digits is 8640, while the sum is 36.

The square root of 51381918 is about 7168.1181630886. The cubic root of 51381918 is about 371.7663725563.

It can be divided in two parts, 5138 and 1918, that added together give a square (7056 = 84²).

The spelling of 51381918 in words is "fifty-one million, three hundred eighty-one thousand, nine hundred eighteen".