1265177981 has 2 divisors, whose sum is σ = 1265177982. Its totient is φ = 1265177980.

The previous prime is 1265177971. The next prime is 1265177989. The reversal of 1265177981 is 1897715621.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 1122853081 + 142324900 = 33509^2 + 11930^2 .

It is an emirp because it is prime and its reverse (1897715621) is a distict prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-1265177981 is a prime.

It is a super-2 number, since 2×1265177981² = 3201350647214472722, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1265177989) 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, 632588990 + 632588991.

It is an arithmetic number, because the mean of its divisors is an integer number (632588991).

Almost surely, 2^1265177981 is an apocalyptic number.

It is an amenable number.

1265177981 is a deficient number, since it is larger than the sum of its proper divisors (1).

1265177981 is an equidigital number, since it uses as much as digits as its factorization.

1265177981 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 211680, while the sum is 47.

The square root of 1265177981 is about 35569.3404633822. The cubic root of 1265177981 is about 1081.5598120259.

The spelling of 1265177981 in words is "one billion, two hundred sixty-five million, one hundred seventy-seven thousand, nine hundred eighty-one".