1261655519 has 2 divisors, whose sum is σ = 1261655520. Its totient is φ = 1261655518.

The previous prime is 1261655503. The next prime is 1261655543. The reversal of 1261655519 is 9155561621.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 1261655519 - 2⁴ = 1261655503 is a prime.

It is a super-2 number, since 2×1261655519² = 3183549297246318722, which contains 22 as substring.

It is a Sophie Germain prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1261655579) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 630827759 + 630827760.

It is an arithmetic number, because the mean of its divisors is an integer number (630827760).

Almost surely, 2^1261655519 is an apocalyptic number.

1261655519 is a deficient number, since it is larger than the sum of its proper divisors (1).

1261655519 is an equidigital number, since it uses as much as digits as its factorization.

1261655519 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 81000, while the sum is 41.

The square root of 1261655519 is about 35519.7905258463. The cubic root of 1261655519 is about 1080.5551327019. Note that the first 3 decimals are identical.

The spelling of 1261655519 in words is "one billion, two hundred sixty-one million, six hundred fifty-five thousand, five hundred nineteen".