51520421 has 8 divisors (see below), whose sum is σ = 54621504. Its totient is φ = 48427200.

The previous prime is 51520411. The next prime is 51520423. The reversal of 51520421 is 12402515.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 51520421 - 2¹⁰ = 51519397 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a junction number, because it is equal to n+sod(n) for n = 51520393 and 51520402.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (51520423) 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 7 ways as a sum of consecutive naturals, for example, 16646 + ... + 19496.

It is an arithmetic number, because the mean of its divisors is an integer number (6827688).

Almost surely, 2^51520421 is an apocalyptic number.

It is an amenable number.

51520421 is a deficient number, since it is larger than the sum of its proper divisors (3101083).

51520421 is a wasteful number, since it uses less digits than its factorization.

51520421 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3931.

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

The square root of 51520421 is about 7177.7727046766. The cubic root of 51520421 is about 372.1001122816.

Adding to 51520421 its reverse (12402515), we get a palindrome (63922936).

The spelling of 51520421 in words is "fifty-one million, five hundred twenty thousand, four hundred twenty-one".