51221321 has 8 divisors (see below), whose sum is σ = 54232320. Its totient is φ = 48241872.

The previous prime is 51221297. The next prime is 51221327. The reversal of 51221321 is 12312215.

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 51221321 - 2²² = 47027017 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 51221321.

It is not an unprimeable number, because it can be changed into a prime (51221327) 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, 4505 + ... + 11078.

It is an arithmetic number, because the mean of its divisors is an integer number (6779040).

Almost surely, 2^51221321 is an apocalyptic number.

It is an amenable number.

51221321 is a deficient number, since it is larger than the sum of its proper divisors (3010999).

51221321 is a wasteful number, since it uses less digits than its factorization.

51221321 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 15775.

The product of its digits is 120, while the sum is 17.

The square root of 51221321 is about 7156.9072230957. The cubic root of 51221321 is about 371.3786429295.

Adding to 51221321 its reverse (12312215), we get a palindrome (63533536).

The spelling of 51221321 in words is "fifty-one million, two hundred twenty-one thousand, three hundred twenty-one".