51021380 has 12 divisors (see below), whose sum is σ = 107144940. Its totient is φ = 20408544.

The previous prime is 51021331. The next prime is 51021391. The reversal of 51021380 is 8312015.

It can be written as a sum of positive squares in 2 ways, for example, as 10086976 + 40934404 = 3176^2 + 6398^2 .

It is a Harshad number since it is a multiple of its sum of digits (20), and also a Moran number because the ratio is a prime number: 2551069 = 51021380 / (5 + 1 + 0 + 2 + 1 + 3 + 8 + 0).

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1275515 + ... + 1275554.

It is an arithmetic number, because the mean of its divisors is an integer number (8928745).

Almost surely, 2^51021380 is an apocalyptic number.

It is an amenable number.

51021380 is an abundant number, since it is smaller than the sum of its proper divisors (56123560).

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

51021380 is a wasteful number, since it uses less digits than its factorization.

51021380 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2551078 (or 2551076 counting only the distinct ones).

The product of its (nonzero) digits is 240, while the sum is 20.

The square root of 51021380 is about 7142.9251711046. The cubic root of 51021380 is about 370.8947907513.

Adding to 51021380 its reverse (8312015), we get a palindrome (59333395).

The spelling of 51021380 in words is "fifty-one million, twenty-one thousand, three hundred eighty".