51279840 has 144 divisors (see below), whose sum is σ = 176904000. Its totient is φ = 13526016.

The previous prime is 51279829. The next prime is 51279853. The reversal of 51279840 is 4897215.

It is a tau number, because it is divible by the number of its divisors (144).

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a junction number, because it is equal to n+sod(n) for n = 51279795 and 51279804.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 214441 + ... + 214679.

It is an arithmetic number, because the mean of its divisors is an integer number (1228500).

Almost surely, 2^51279840 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 51279840, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (88452000).

51279840 is an abundant number, since it is smaller than the sum of its proper divisors (125624160).

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

51279840 is a wasteful number, since it uses less digits than its factorization.

51279840 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 409 (or 398 counting only the distinct ones).

The product of its (nonzero) digits is 20160, while the sum is 36.

The square root of 51279840 is about 7160.9943443631. The cubic root of 51279840 is about 371.5200191851.

The spelling of 51279840 in words is "fifty-one million, two hundred seventy-nine thousand, eight hundred forty".