21003640205 has 8 divisors (see below), whose sum is σ = 25371285504. Its totient is φ = 16691634000.

The previous prime is 21003640201. The next prime is 21003640213. The reversal of 21003640205 is 50204630012.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 21003640205 - 2² = 21003640201 is a prime.

It is a super-2 number, since 2×21003640205² (a number of 21 digits) contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21003640201) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 13908941 + ... + 13910450.

It is an arithmetic number, because the mean of its divisors is an integer number (3171410688).

Almost surely, 2^21003640205 is an apocalyptic number.

It is an amenable number.

21003640205 is a deficient number, since it is larger than the sum of its proper divisors (4367645299).

21003640205 is a wasteful number, since it uses less digits than its factorization.

21003640205 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 27819547.

The product of its (nonzero) digits is 1440, while the sum is 23.

The spelling of 21003640205 in words is "twenty-one billion, three million, six hundred forty thousand, two hundred five".