1233021991 has 2 divisors, whose sum is σ = 1233021992. Its totient is φ = 1233021990.

The previous prime is 1233021983. The next prime is 1233022009. The reversal of 1233021991 is 1991203321.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 1233021991 - 2³ = 1233021983 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1233421991) 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 as a sum of consecutive naturals, namely, 616510995 + 616510996.

It is an arithmetic number, because the mean of its divisors is an integer number (616510996).

Almost surely, 2^1233021991 is an apocalyptic number.

1233021991 is a deficient number, since it is larger than the sum of its proper divisors (1).

1233021991 is an equidigital number, since it uses as much as digits as its factorization.

1233021991 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 2916, while the sum is 31.

The square root of 1233021991 is about 35114.4128670835. The cubic root of 1233021991 is about 1072.3180278923.

The spelling of 1233021991 in words is "one billion, two hundred thirty-three million, twenty-one thousand, nine hundred ninety-one".