1231155515511 has 12 divisors (see below), whose sum is σ = 1778497863480. Its totient is φ = 820695519600.

The previous prime is 1231155515503. The next prime is 1231155515549. The reversal of 1231155515511 is 1155155511321.

1231155515511 is a `hidden beast` number, since 1 + 2 + 3 + 1 + 1 + 55 + 51 + 551 + 1 = 666.

It is not a de Polignac number, because 1231155515511 - 2³ = 1231155515503 is a prime.

It is a super-2 number, since 2×1231155515511² (a number of 25 digits) contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1231155515501) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 6131040 + ... + 6328661.

It is an arithmetic number, because the mean of its divisors is an integer number (148208155290).

Almost surely, 2^{1231155515511} is an apocalyptic number.

1231155515511 is a deficient number, since it is larger than the sum of its proper divisors (547342347969).

1231155515511 is a wasteful number, since it uses less digits than its factorization.

1231155515511 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 12470686 (or 12470683 counting only the distinct ones).

The product of its digits is 18750, while the sum is 36.

The spelling of 1231155515511 in words is "one trillion, two hundred thirty-one billion, one hundred fifty-five million, five hundred fifteen thousand, five hundred eleven".