1551322321 has 4 divisors (see below), whose sum is σ = 1552927552. Its totient is φ = 1549717092.

The previous prime is 1551322319. The next prime is 1551322351. The reversal of 1551322321 is 1232231551.

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: 1232231551 = 5273 ⋅233687.

It is a cyclic number.

It is not a de Polignac number, because 1551322321 - 2¹ = 1551322319 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1551322351) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 801165 + ... + 803098.

It is an arithmetic number, because the mean of its divisors is an integer number (388231888).

Almost surely, 2^1551322321 is an apocalyptic number.

It is an amenable number.

1551322321 is a deficient number, since it is larger than the sum of its proper divisors (1605231).

1551322321 is an equidigital number, since it uses as much as digits as its factorization.

1551322321 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1605230.

The product of its digits is 1800, while the sum is 25.

The square root of 1551322321 is about 39386.8292834039. The cubic root of 1551322321 is about 1157.6235336902.

Adding to 1551322321 its reverse (1232231551), we get a palindrome (2783553872).

The spelling of 1551322321 in words is "one billion, five hundred fifty-one million, three hundred twenty-two thousand, three hundred twenty-one".