51978240 has 224 divisors, whose sum is σ = 188732160. Its totient is φ = 13565952.

The previous prime is 51978239. The next prime is 51978247. The reversal of 51978240 is 4287915.

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 = 51978195 and 51978204.

It is not an unprimeable number, because it can be changed into a prime (51978247) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 1105897 + ... + 1105943.

Almost surely, 2^51978240 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 51978240, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (94366080).

51978240 is an abundant number, since it is smaller than the sum of its proper divisors (136753920).

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

51978240 is an equidigital number, since it uses as much as digits as its factorization.

51978240 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 87 (or 57 counting only the distinct ones).

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

The square root of 51978240 is about 7209.5936085191. The cubic root of 51978240 is about 373.1990446724.

The spelling of 51978240 in words is "fifty-one million, nine hundred seventy-eight thousand, two hundred forty".