51125220 has 72 divisors (see below), whose sum is σ = 155675520. Its totient is φ = 13581120.

The previous prime is 51125201. The next prime is 51125279. The reversal of 51125220 is 2252115.

It is a super-2 number, since 2×51125220² = 5227576240096800, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (18).

It is a junction number, because it is equal to n+sod(n) for n = 51125193 and 51125202.

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, 77251 + ... + 77909.

It is an arithmetic number, because the mean of its divisors is an integer number (2162160).

Almost surely, 2^51125220 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 51125220, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (77837760).

51125220 is an abundant number, since it is smaller than the sum of its proper divisors (104550300).

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

51125220 is a wasteful number, since it uses less digits than its factorization.

51125220 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1105 (or 1100 counting only the distinct ones).

The product of its (nonzero) digits is 200, while the sum is 18.

The square root of 51125220 is about 7150.1902072602. The cubic root of 51125220 is about 371.1462383898.

Adding to 51125220 its reverse (2252115), we get a palindrome (53377335).

The spelling of 51125220 in words is "fifty-one million, one hundred twenty-five thousand, two hundred twenty".