11781121455 has 24 divisors (see below), whose sum is σ = 20479149600. Its totient is φ = 6265252800.

The previous prime is 11781121409. The next prime is 11781121463. The reversal of 11781121455 is 55412118711.

It is a happy number.

11781121455 is a `hidden beast` number, since 1 + 1 + 7 + 81 + 121 + 455 = 666.

It is not a de Polignac number, because 11781121455 - 2⁸ = 11781121199 is a prime.

It is a super-2 number, since 2×11781121455² (a number of 21 digits) contains 22 as substring.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 359371 + ... + 390780.

It is an arithmetic number, because the mean of its divisors is an integer number (853297900).

Almost surely, 2^11781121455 is an apocalyptic number.

11781121455 is a gapful number since it is divisible by the number (15) formed by its first and last digit.

11781121455 is a deficient number, since it is larger than the sum of its proper divisors (8698028145).

11781121455 is a wasteful number, since it uses less digits than its factorization.

11781121455 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 750511 (or 750508 counting only the distinct ones).

The product of its digits is 11200, while the sum is 36.

The spelling of 11781121455 in words is "eleven billion, seven hundred eighty-one million, one hundred twenty-one thousand, four hundred fifty-five".