1261557855616 has 32 divisors (see below), whose sum is σ = 2513516154480. Its totient is φ = 630714585600.

The previous prime is 1261557855563. The next prime is 1261557855661. The reversal of 1261557855616 is 6165587551621.

It is a tau number, because it is divible by the number of its divisors (32).

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 3 ways as a sum of consecutive naturals, for example, 769605 + ... + 1765051.

Almost surely, 2^{1261557855616} is an apocalyptic number.

1261557855616 is a gapful number since it is divisible by the number (16) formed by its first and last digit.

It is an amenable number.

1261557855616 is a deficient number, since it is larger than the sum of its proper divisors (1251958298864).

1261557855616 is an frugal number, since it uses more digits than its factorization.

1261557855616 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1005362 (or 1005350 counting only the distinct ones).

The product of its digits is 15120000, while the sum is 58.

The spelling of 1261557855616 in words is "one trillion, two hundred sixty-one billion, five hundred fifty-seven million, eight hundred fifty-five thousand, six hundred sixteen".