21533107644 has 36 divisors (see below), whose sum is σ = 54440746360. Its totient is φ = 7176405600.

The previous prime is 21533107639. The next prime is 21533107667. The reversal of 21533107644 is 44670133512.

21533107644 is a `hidden beast` number, since 2 + 1 + 5 + 3 + 3 + 1 + 0 + 7 + 644 = 666.

It is a tau number, because it is divible by the number of its divisors (36).

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a junction number, because it is equal to n+sod(n) for n = 21533107599 and 21533107608.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 159522 + ... + 261750.

Almost surely, 2^21533107644 is an apocalyptic number.

It is an amenable number.

21533107644 is an abundant number, since it is smaller than the sum of its proper divisors (32907638716).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21533107644 is a wasteful number, since it uses less digits than its factorization.

21533107644 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 108090 (or 108085 counting only the distinct ones).

The product of its (nonzero) digits is 60480, while the sum is 36.

The spelling of 21533107644 in words is "twenty-one billion, five hundred thirty-three million, one hundred seven thousand, six hundred forty-four".