21204440124 has 72 divisors (see below), whose sum is σ = 57621645648. Its totient is φ = 6051386880.

The previous prime is 21204440111. The next prime is 21204440129. The reversal of 21204440124 is 42104440212.

It is a super-2 number, since 2×21204440124² (a number of 21 digits) contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 21204440094 and 21204440103.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21204440129) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 497562 + ... + 538494.

It is an arithmetic number, because the mean of its divisors is an integer number (800300634).

Almost surely, 2^21204440124 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21204440124, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (28810822824).

21204440124 is an abundant number, since it is smaller than the sum of its proper divisors (36417205524).

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

21204440124 is a wasteful number, since it uses less digits than its factorization.

21204440124 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 41835 (or 41826 counting only the distinct ones).

The product of its (nonzero) digits is 2048, while the sum is 24.

Adding to 21204440124 its reverse (42104440212), we get a palindrome (63308880336).

The spelling of 21204440124 in words is "twenty-one billion, two hundred four million, four hundred forty thousand, one hundred twenty-four".