21044401040 has 80 divisors (see below), whose sum is σ = 52731000000. Its totient is φ = 7764481536.

The previous prime is 21044401039. The next prime is 21044401043. The reversal of 21044401040 is 4010444012.

It is a happy number.

It is a tau number, because it is divible by the number of its divisors (80).

It is a Harshad number since it is a multiple of its sum of digits (20).

It is not an unprimeable number, because it can be changed into a prime (21044401043) 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, 1552211 + ... + 1565709.

It is an arithmetic number, because the mean of its divisors is an integer number (659137500).

Almost surely, 2^21044401040 is an apocalyptic number.

21044401040 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 21044401040, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (26365500000).

21044401040 is an abundant number, since it is smaller than the sum of its proper divisors (31686598960).

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

21044401040 is a wasteful number, since it uses less digits than its factorization.

21044401040 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 15024 (or 15018 counting only the distinct ones).

The product of its (nonzero) digits is 512, while the sum is 20.

Adding to 21044401040 its reverse (4010444012), we get a palindrome (25054845052).

The spelling of 21044401040 in words is "twenty-one billion, forty-four million, four hundred one thousand, forty".