1215561187755 has 12 divisors (see below), whose sum is σ = 2106972725520. Its totient is φ = 648299300112.

The previous prime is 1215561187747. The next prime is 1215561187759. The reversal of 1215561187755 is 5577811655121.

1215561187755 is a `hidden beast` number, since 1 + 2 + 1 + 5 + 561 + 1 + 8 + 7 + 75 + 5 = 666.

It is not a de Polignac number, because 1215561187755 - 2³ = 1215561187747 is a prime.

It is a Smith number, since the sum of its digits (54) coincides with the sum of the digits of its prime factors.

It is not an unprimeable number, because it can be changed into a prime (1215561187759) 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 in 11 ways as a sum of consecutive naturals, for example, 13506235375 + ... + 13506235464.

It is an arithmetic number, because the mean of its divisors is an integer number (175581060460).

Almost surely, 2^{1215561187755} is an apocalyptic number.

1215561187755 is a gapful number since it is divisible by the number (15) formed by its first and last digit.

1215561187755 is a deficient number, since it is larger than the sum of its proper divisors (891411537765).

1215561187755 is a wasteful number, since it uses less digits than its factorization.

1215561187755 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 27012470850 (or 27012470847 counting only the distinct ones).

The product of its digits is 2940000, while the sum is 54.

The spelling of 1215561187755 in words is "one trillion, two hundred fifteen billion, five hundred sixty-one million, one hundred eighty-seven thousand, seven hundred fifty-five".