1321056403 has 4 divisors (see below), whose sum is σ = 1321144360. Its totient is φ = 1320968448.

The previous prime is 1321056389. The next prime is 1321056409. The reversal of 1321056403 is 3046501231.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length, and also an emirpimes, since its reverse is a distinct semiprime: 3046501231 = 337 ⋅9040063.

It is a cyclic number.

It is not a de Polignac number, because 1321056403 - 2²¹ = 1318959251 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1321056409) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 15150 + ... + 53587.

It is an arithmetic number, because the mean of its divisors is an integer number (330286090).

Almost surely, 2^1321056403 is an apocalyptic number.

1321056403 is a deficient number, since it is larger than the sum of its proper divisors (87957).

1321056403 is an equidigital number, since it uses as much as digits as its factorization.

1321056403 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 87956.

The product of its (nonzero) digits is 2160, while the sum is 25.

The square root of 1321056403 is about 36346.3396093747. The cubic root of 1321056403 is about 1097.2538671069.

Adding to 1321056403 its reverse (3046501231), we get a palindrome (4367557634).

The spelling of 1321056403 in words is "one billion, three hundred twenty-one million, fifty-six thousand, four hundred three".