51021821 has 8 divisors (see below), whose sum is σ = 53782080. Its totient is φ = 48269088.

The previous prime is 51021793. The next prime is 51021827. The reversal of 51021821 is 12812015.

It is a happy number.

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 51021821 - 2¹⁰ = 51020797 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 51021793 and 51021802.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (51021827) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 16985 + ... + 19761.

It is an arithmetic number, because the mean of its divisors is an integer number (6722760).

Almost surely, 2^51021821 is an apocalyptic number.

It is an amenable number.

51021821 is a deficient number, since it is larger than the sum of its proper divisors (2760259).

51021821 is a wasteful number, since it uses less digits than its factorization.

51021821 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3763.

The product of its (nonzero) digits is 160, while the sum is 20.

The square root of 51021821 is about 7142.9560407439. The cubic root of 51021821 is about 370.8958593499.

Adding to 51021821 its reverse (12812015), we get a palindrome (63833836).

The spelling of 51021821 in words is "fifty-one million, twenty-one thousand, eight hundred twenty-one".