21100404440 has 32 divisors (see below), whose sum is σ = 48580004880. Its totient is φ = 8243878272.

The previous prime is 21100404427. The next prime is 21100404461. The reversal of 21100404440 is 4440400112.

It is a happy number.

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

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 6132119 + ... + 6135558.

Almost surely, 2^21100404440 is an apocalyptic number.

21100404440 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21100404440 is an abundant number, since it is smaller than the sum of its proper divisors (27479600440).

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

21100404440 is a wasteful number, since it uses less digits than its factorization.

21100404440 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 12267731 (or 12267727 counting only the distinct ones).

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

Adding to 21100404440 its reverse (4440400112), we get a palindrome (25540804552).

The spelling of 21100404440 in words is "twenty-one billion, one hundred million, four hundred four thousand, four hundred forty".