21154533213544 has 64 divisors (see below), whose sum is σ = 41948444851200. Its totient is φ = 9985009757184.

The previous prime is 21154533213529. The next prime is 21154533213547. The reversal of 21154533213544 is 44531233545112.

It is a self number, because there is not a number n which added to its sum of digits gives 21154533213544.

It is not an unprimeable number, because it can be changed into a prime (21154533213547) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 9660337 + ... + 11646079.

It is an arithmetic number, because the mean of its divisors is an integer number (655444450800).

Almost surely, 2^{21154533213544} is an apocalyptic number.

It is an amenable number.

21154533213544 is a deficient number, since it is larger than the sum of its proper divisors (20793911637656).

21154533213544 is a wasteful number, since it uses less digits than its factorization.

21154533213544 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1986802 (or 1986798 counting only the distinct ones).

The product of its digits is 864000, while the sum is 43.

Adding to 21154533213544 its reverse (44531233545112), we get a palindrome (65685766758656).

The spelling of 21154533213544 in words is "twenty-one trillion, one hundred fifty-four billion, five hundred thirty-three million, two hundred thirteen thousand, five hundred forty-four".