51021221 has 4 divisors (see below), whose sum is σ = 51201792. Its totient is φ = 50840652.

The previous prime is 51021197. The next prime is 51021241. The reversal of 51021221 is 12212015.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also an emirpimes, since its reverse is a distinct semiprime: 12212015 = 5 ⋅2442403.

It is a cyclic number.

It is not a de Polignac number, because 51021221 - 2¹⁰ = 51020197 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 51021196 and 51021205.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (51021241) 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 3 ways as a sum of consecutive naturals, for example, 89861 + ... + 90426.

It is an arithmetic number, because the mean of its divisors is an integer number (12800448).

Almost surely, 2^51021221 is an apocalyptic number.

It is an amenable number.

51021221 is a deficient number, since it is larger than the sum of its proper divisors (180571).

51021221 is a wasteful number, since it uses less digits than its factorization.

51021221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 180570.

The product of its (nonzero) digits is 40, while the sum is 14.

The square root of 51021221 is about 7142.9140412020. The cubic root of 51021221 is about 370.8944054727.

Adding to 51021221 its reverse (12212015), we get a palindrome (63233236).

The spelling of 51021221 in words is "fifty-one million, twenty-one thousand, two hundred twenty-one".