21124100040 has 128 divisors (see below), whose sum is σ = 67271679360. Its totient is φ = 5288177664.

The previous prime is 21124100027. The next prime is 21124100087. The reversal of 21124100040 is 4000142112.

It is a Harshad number since it is a multiple of its sum of digits (15).

It is a junction number, because it is equal to n+sod(n) for n = 21124099992 and 21124100019.

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 31 ways as a sum of consecutive naturals, for example, 796839 + ... + 822921.

It is an arithmetic number, because the mean of its divisors is an integer number (525559995).

Almost surely, 2^21124100040 is an apocalyptic number.

21124100040 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21124100040, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (33635839680).

21124100040 is an abundant number, since it is smaller than the sum of its proper divisors (46147579320).

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

21124100040 is a wasteful number, since it uses less digits than its factorization.

21124100040 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 26511 (or 26507 counting only the distinct ones).

The product of its (nonzero) digits is 64, while the sum is 15.

Adding to 21124100040 its reverse (4000142112), we get a palindrome (25124242152).

The spelling of 21124100040 in words is "twenty-one billion, one hundred twenty-four million, one hundred thousand, forty".