1221033391 has 2 divisors, whose sum is σ = 1221033392. Its totient is φ = 1221033390.

The previous prime is 1221033349. The next prime is 1221033427. The reversal of 1221033391 is 1933301221.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 1221033391 - 2²⁷ = 1086815663 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1221033091) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 610516695 + 610516696.

It is an arithmetic number, because the mean of its divisors is an integer number (610516696).

Almost surely, 2^1221033391 is an apocalyptic number.

1221033391 is a deficient number, since it is larger than the sum of its proper divisors (1).

1221033391 is an equidigital number, since it uses as much as digits as its factorization.

1221033391 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 972, while the sum is 25.

The square root of 1221033391 is about 34943.2882110428. The cubic root of 1221033391 is about 1068.8313414556.

The spelling of 1221033391 in words is "one billion, two hundred twenty-one million, thirty-three thousand, three hundred ninety-one".