21001044401 has 32 divisors (see below), whose sum is σ = 23535525888. Its totient is φ = 18637344000.

The previous prime is 21001044397. The next prime is 21001044403. The reversal of 21001044401 is 10444010012.

It is a cyclic number.

It is not a de Polignac number, because 21001044401 - 2² = 21001044397 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (17).

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 21001044401.

It is not an unprimeable number, because it can be changed into a prime (21001044403) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 9328526 + ... + 9330776.

It is an arithmetic number, because the mean of its divisors is an integer number (735485184).

Almost surely, 2^21001044401 is an apocalyptic number.

It is an amenable number.

21001044401 is a deficient number, since it is larger than the sum of its proper divisors (2534481487).

21001044401 is a wasteful number, since it uses less digits than its factorization.

21001044401 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2621.

The product of its (nonzero) digits is 128, while the sum is 17.

Adding to 21001044401 its reverse (10444010012), we get a palindrome (31445054413).

The spelling of 21001044401 in words is "twenty-one billion, one million, forty-four thousand, four hundred one".