1223965991 has 2 divisors, whose sum is σ = 1223965992. Its totient is φ = 1223965990.

The previous prime is 1223965987. The next prime is 1223966041. The reversal of 1223965991 is 1995693221.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 1223965991 - 2² = 1223965987 is a prime.

It is a super-2 number, since 2×1223965991² = 2996185494249224162, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1223967991) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 611982995 + 611982996.

It is an arithmetic number, because the mean of its divisors is an integer number (611982996).

Almost surely, 2^1223965991 is an apocalyptic number.

1223965991 is a deficient number, since it is larger than the sum of its proper divisors (1).

1223965991 is an equidigital number, since it uses as much as digits as its factorization.

1223965991 is an evil number, because the sum of its binary digits is even.

The product of its digits is 262440, while the sum is 47.

The square root of 1223965991 is about 34985.2253244137. The cubic root of 1223965991 is about 1069.6863409394.

The spelling of 1223965991 in words is "one billion, two hundred twenty-three million, nine hundred sixty-five thousand, nine hundred ninety-one".