21044199997 has 4 divisors (see below), whose sum is σ = 21046683996. Its totient is φ = 21041716000.

The previous prime is 21044199983. The next prime is 21044200003. The reversal of 21044199997 is 79999144012.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 7926162841 + 13118037156 = 89029^2 + 114534^2 .

It is a cyclic number.

It is not a de Polignac number, because 21044199997 - 2¹⁵ = 21044167229 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21044199697) 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, 1229248 + ... + 1246249.

It is an arithmetic number, because the mean of its divisors is an integer number (5261670999).

Almost surely, 2^21044199997 is an apocalyptic number.

It is an amenable number.

21044199997 is a deficient number, since it is larger than the sum of its proper divisors (2483999).

21044199997 is an equidigital number, since it uses as much as digits as its factorization.

21044199997 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2483998.

The product of its (nonzero) digits is 1469664, while the sum is 55.

The spelling of 21044199997 in words is "twenty-one billion, forty-four million, one hundred ninety-nine thousand, nine hundred ninety-seven".