1065643991 has 2 divisors, whose sum is σ = 1065643992. Its totient is φ = 1065643990.

The previous prime is 1065643987. The next prime is 1065644011. The reversal of 1065643991 is 1993465601.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 1065643991 - 2² = 1065643987 is a prime.

It is a super-2 number, since 2×1065643991² = 2271194231108816162, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1065643921) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 532821995 + 532821996.

It is an arithmetic number, because the mean of its divisors is an integer number (532821996).

Almost surely, 2^1065643991 is an apocalyptic number.

1065643991 is a deficient number, since it is larger than the sum of its proper divisors (1).

1065643991 is an equidigital number, since it uses as much as digits as its factorization.

1065643991 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 174960, while the sum is 44.

The square root of 1065643991 is about 32644.2030228952. The cubic root of 1065643991 is about 1021.4192696088.

The spelling of 1065643991 in words is "one billion, sixty-five million, six hundred forty-three thousand, nine hundred ninety-one".