1261016646565 has 32 divisors (see below), whose sum is σ = 1642738406400. Its totient is φ = 923742420480.

The previous prime is 1261016646541. The next prime is 1261016646581. The reversal of 1261016646565 is 5656466101621.

It is not a de Polignac number, because 1261016646565 - 2²¹ = 1261014549413 is a prime.

It is a congruent number.

It is an unprimeable number.

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 in 31 ways as a sum of consecutive naturals, for example, 4626220 + ... + 4891210.

It is an arithmetic number, because the mean of its divisors is an integer number (51335575200).

Almost surely, 2^{1261016646565} is an apocalyptic number.

It is an amenable number.

1261016646565 is a deficient number, since it is larger than the sum of its proper divisors (381721759835).

1261016646565 is a wasteful number, since it uses less digits than its factorization.

1261016646565 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 265597.

The product of its (nonzero) digits is 1555200, while the sum is 49.

The spelling of 1261016646565 in words is "one trillion, two hundred sixty-one billion, sixteen million, six hundred forty-six thousand, five hundred sixty-five".