11953543681 has 4 divisors (see below), whose sum is σ = 11953916352. Its totient is φ = 11953171012.

The previous prime is 11953543643. The next prime is 11953543687. The reversal of 11953543681 is 18634535911.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-11953543681 is a prime.

It is a super-2 number, since 2×11953543681² (a number of 21 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (11953543687) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 133165 + ... + 204058.

It is an arithmetic number, because the mean of its divisors is an integer number (2988479088).

Almost surely, 2^11953543681 is an apocalyptic number.

It is an amenable number.

11953543681 is a deficient number, since it is larger than the sum of its proper divisors (372671).

11953543681 is an equidigital number, since it uses as much as digits as its factorization.

11953543681 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 372670.

The product of its digits is 388800, while the sum is 46.

It can be divided in two parts, 119535 and 43681, that added together give a square (163216 = 404²).

The spelling of 11953543681 in words is "eleven billion, nine hundred fifty-three million, five hundred forty-three thousand, six hundred eighty-one".