21200016928549 has 4 divisors (see below), whose sum is σ = 21200036682700. Its totient is φ = 21199997174400.

The previous prime is 21200016928547. The next prime is 21200016928567. The reversal of 21200016928549 is 94582961000212.

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 10503238356900 + 10696778571649 = 3240870^2 + 3270593^2 .

It is a cyclic number.

It is not a de Polignac number, because 21200016928549 - 2¹ = 21200016928547 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 (21200016928547) 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, 8168802 + ... + 10446499.

It is an arithmetic number, because the mean of its divisors is an integer number (5300009170675).

Almost surely, 2^{21200016928549} is an apocalyptic number.

It is an amenable number.

21200016928549 is a deficient number, since it is larger than the sum of its proper divisors (19754151).

21200016928549 is a wasteful number, since it uses less digits than its factorization.

21200016928549 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 19754150.

The product of its (nonzero) digits is 622080, while the sum is 49.

The spelling of 21200016928549 in words is "twenty-one trillion, two hundred billion, sixteen million, nine hundred twenty-eight thousand, five hundred forty-nine".