51308640 has 240 divisors, whose sum is σ = 187708752. Its totient is φ = 13188096.

The previous prime is 51308629. The next prime is 51308657. The reversal of 51308640 is 4680315.

51308640 is a `hidden beast` number, since 5 + 13 + 0 + 8 + 640 = 666.

It is a tau number, because it is divible by the number of its divisors (240).

It is a Harshad number since it is a multiple of its sum of digits (27).

It is a congruent number.

It is an unprimeable number.

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 39 ways as a sum of consecutive naturals, for example, 479467 + ... + 479573.

Almost surely, 2^51308640 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 51308640, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (93854376).

51308640 is an abundant number, since it is smaller than the sum of its proper divisors (136400112).

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

51308640 is a wasteful number, since it uses less digits than its factorization.

51308640 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 171 (or 154 counting only the distinct ones).

The product of its (nonzero) digits is 2880, while the sum is 27.

The square root of 51308640 is about 7163.0049560223. The cubic root of 51308640 is about 371.5895577152.

Adding to 51308640 its reverse (4680315), we get a palindrome (55988955).

The spelling of 51308640 in words is "fifty-one million, three hundred eight thousand, six hundred forty".