51521420 has 48 divisors (see below), whose sum is σ = 112317408. Its totient is φ = 19837440.

The previous prime is 51521401. The next prime is 51521423. The reversal of 51521420 is 2412515.

It is a Harshad number since it is a multiple of its sum of digits (20).

It is a junction number, because it is equal to n+sod(n) for n = 51521392 and 51521401.

It is not an unprimeable number, because it can be changed into a prime (51521423) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 67682 + ... + 68438.

It is an arithmetic number, because the mean of its divisors is an integer number (2339946).

Almost surely, 2^51521420 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 51521420, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (56158704).

51521420 is an abundant number, since it is smaller than the sum of its proper divisors (60795988).

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

51521420 is a wasteful number, since it uses less digits than its factorization.

51521420 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 890 (or 888 counting only the distinct ones).

The product of its (nonzero) digits is 400, while the sum is 20.

The square root of 51521420 is about 7177.8422941717. The cubic root of 51521420 is about 372.1025173189.

Adding to 51521420 its reverse (2412515), we get a palindrome (53933935).

The spelling of 51521420 in words is "fifty-one million, five hundred twenty-one thousand, four hundred twenty".