1265992561 has 2 divisors, whose sum is σ = 1265992562. Its totient is φ = 1265992560.

The previous prime is 1265992543. The next prime is 1265992573. The reversal of 1265992561 is 1652995621.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 975937600 + 290054961 = 31240^2 + 17031^2 .

It is a cyclic number.

It is not a de Polignac number, because 1265992561 - 2⁵ = 1265992529 is a prime.

It is not a weakly prime, because it can be changed into another prime (1265992501) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 632996280 + 632996281.

It is an arithmetic number, because the mean of its divisors is an integer number (632996281).

Almost surely, 2^1265992561 is an apocalyptic number.

It is an amenable number.

1265992561 is a deficient number, since it is larger than the sum of its proper divisors (1).

1265992561 is an equidigital number, since it uses as much as digits as its factorization.

1265992561 is an evil number, because the sum of its binary digits is even.

The product of its digits is 291600, while the sum is 46.

The square root of 1265992561 is about 35580.7892127198. The cubic root of 1265992561 is about 1081.7918816089.

The spelling of 1265992561 in words is "one billion, two hundred sixty-five million, nine hundred ninety-two thousand, five hundred sixty-one".