11661635421 has 32 divisors (see below), whose sum is σ = 18367845120. Its totient is φ = 7296075072.

The previous prime is 11661635413. The next prime is 11661635431. The reversal of 11661635421 is 12453616611.

11661635421 is a `hidden beast` number, since 1 + 1 + 6 + 616 + 35 + 4 + 2 + 1 = 666.

It is not a de Polignac number, because 11661635421 - 2³ = 11661635413 is a prime.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (11661635431) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 144246 + ... + 210071.

It is an arithmetic number, because the mean of its divisors is an integer number (573995160).

Almost surely, 2^11661635421 is an apocalyptic number.

It is an amenable number.

11661635421 is a deficient number, since it is larger than the sum of its proper divisors (6706209699).

11661635421 is a wasteful number, since it uses less digits than its factorization.

11661635421 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 354402 (or 354396 counting only the distinct ones).

The product of its digits is 25920, while the sum is 36.

The spelling of 11661635421 in words is "eleven billion, six hundred sixty-one million, six hundred thirty-five thousand, four hundred twenty-one".