1321503551 has 4 divisors (see below), whose sum is σ = 1399239072. Its totient is φ = 1243768032.

The previous prime is 1321503541. The next prime is 1321503553. The reversal of 1321503551 is 1553051231.

It is a happy number.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 1321503551 - 2⁶ = 1321503487 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 1321503551.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1321503553) 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, 38867735 + ... + 38867768.

It is an arithmetic number, because the mean of its divisors is an integer number (349809768).

Almost surely, 2^1321503551 is an apocalyptic number.

1321503551 is a deficient number, since it is larger than the sum of its proper divisors (77735521).

1321503551 is an equidigital number, since it uses as much as digits as its factorization.

1321503551 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 77735520.

The product of its (nonzero) digits is 2250, while the sum is 26.

The square root of 1321503551 is about 36352.4902998405. The cubic root of 1321503551 is about 1097.3776517601.

Adding to 1321503551 its reverse (1553051231), we get a palindrome (2874554782).

The spelling of 1321503551 in words is "one billion, three hundred twenty-one million, five hundred three thousand, five hundred fifty-one".