21121404440 has 16 divisors (see below), whose sum is σ = 47523160080. Its totient is φ = 8448561760.

The previous prime is 21121404431. The next prime is 21121404443. The reversal of 21121404440 is 4440412112.

It is a super-2 number, since 2×21121404440² (a number of 21 digits) contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21121404443) 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, 264017516 + ... + 264017595.

It is an arithmetic number, because the mean of its divisors is an integer number (2970197505).

Almost surely, 2^21121404440 is an apocalyptic number.

21121404440 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21121404440 is an abundant number, since it is smaller than the sum of its proper divisors (26401755640).

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

21121404440 is a wasteful number, since it uses less digits than its factorization.

21121404440 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 528035122 (or 528035118 counting only the distinct ones).

The product of its (nonzero) digits is 1024, while the sum is 23.

Adding to 21121404440 its reverse (4440412112), we get a palindrome (25561816552).

The spelling of 21121404440 in words is "twenty-one billion, one hundred twenty-one million, four hundred four thousand, four hundred forty".