51821620 has 24 divisors (see below), whose sum is σ = 109625544. Its totient is φ = 20576256.

The previous prime is 51821591. The next prime is 51821629. The reversal of 51821620 is 2612815.

51821620 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It can be written as a sum of positive squares in 4 ways, for example, as 20034576 + 31787044 = 4476^2 + 5638^2 .

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (51821629) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 6717 + ... + 12196.

It is an arithmetic number, because the mean of its divisors is an integer number (4567731).

Almost surely, 2^51821620 is an apocalyptic number.

It is an amenable number.

51821620 is an abundant number, since it is smaller than the sum of its proper divisors (57803924).

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

51821620 is a wasteful number, since it uses less digits than its factorization.

51821620 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 19059 (or 19057 counting only the distinct ones).

The product of its (nonzero) digits is 960, while the sum is 25.

The square root of 51821620 is about 7198.7234979543. The cubic root of 51821620 is about 372.8238284271.

It can be divided in two parts, 51821 and 620, that added together give a square (52441 = 229²).

The spelling of 51821620 in words is "fifty-one million, eight hundred twenty-one thousand, six hundred twenty".