11961561185401 has 9 divisors (see below), whose sum is σ = 11997335590149. Its totient is φ = 11925893169564.

The previous prime is 11961561185377. The next prime is 11961561185437. The reversal of 11961561185401 is 10458116516911.

The square root of 11961561185401 is 3458549.

It is a perfect power (a square), and thus also a powerful number.

11961561185401 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is not a de Polignac number, because 11961561185401 - 2⁹ = 11961561184889 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (11961561185501) by changing a digit.

It is a polite number, since it can be written in 8 ways as a sum of consecutive naturals, for example, 1200111520 + ... + 1200121486.

Almost surely, 2^{11961561185401} is an apocalyptic number.

11961561185401 is the 3458549-th square number.

11961561185401 is the 1729275-th centered octagonal number.

It is an amenable number.

11961561185401 is a deficient number, since it is larger than the sum of its proper divisors (35774404748).

11961561185401 is an frugal number, since it uses more digits than its factorization.

11961561185401 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 20628 (or 10314 counting only the distinct ones).

The product of its (nonzero) digits is 259200, while the sum is 49.

Multiplying 11961561185401 by its sum of digits (49), we get a square (586116498084649 = 24209843²).

The spelling of 11961561185401 in words is "eleven trillion, nine hundred sixty-one billion, five hundred sixty-one million, one hundred eighty-five thousand, four hundred one".