1221312403 has 2 divisors, whose sum is σ = 1221312404. Its totient is φ = 1221312402.

The previous prime is 1221312383. The next prime is 1221312413. The reversal of 1221312403 is 3042131221.

It is a happy number.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 1221312403 - 2⁵ = 1221312371 is a prime.

It is not a weakly prime, because it can be changed into another prime (1221312413) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 610656201 + 610656202.

It is an arithmetic number, because the mean of its divisors is an integer number (610656202).

Almost surely, 2^1221312403 is an apocalyptic number.

1221312403 is a deficient number, since it is larger than the sum of its proper divisors (1).

1221312403 is an equidigital number, since it uses as much as digits as its factorization.

1221312403 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 288, while the sum is 19.

The square root of 1221312403 is about 34947.2803376743. The cubic root of 1221312403 is about 1068.9127462888.

Adding to 1221312403 its reverse (3042131221), we get a palindrome (4263443624).

The spelling of 1221312403 in words is "one billion, two hundred twenty-one million, three hundred twelve thousand, four hundred three".