21521155124 has 12 divisors (see below), whose sum is σ = 43042310304. Its totient is φ = 9223352184.

The previous prime is 21521155121. The next prime is 21521155129. The reversal of 21521155124 is 42155112512.

21521155124 is an admirable number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21521155121) 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, 384306314 + ... + 384306369.

It is an arithmetic number, because the mean of its divisors is an integer number (3586859192).

Almost surely, 2^21521155124 is an apocalyptic number.

It is an amenable number.

21521155124 is a primitive abundant number, since it is smaller than the sum of its proper divisors, none of which is abundant.

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

21521155124 is a wasteful number, since it uses less digits than its factorization.

21521155124 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 768612694 (or 768612692 counting only the distinct ones).

The product of its digits is 4000, while the sum is 29.

Adding to 21521155124 its reverse (42155112512), we get a palindrome (63676267636).

The spelling of 21521155124 in words is "twenty-one billion, five hundred twenty-one million, one hundred fifty-five thousand, one hundred twenty-four".