21009571220773 has 4 divisors (see below), whose sum is σ = 21009586759020. Its totient is φ = 21009555682528.

The previous prime is 21009571220747. The next prime is 21009571220791. The reversal of 21009571220773 is 37702217590012.

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 6559248576609 + 14450322644164 = 2561103^2 + 3801358^2 .

It is a cyclic number.

It is not a de Polignac number, because 21009571220773 - 2¹⁷ = 21009571089701 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 (21009571220173) 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, 5524840 + ... + 8517217.

It is an arithmetic number, because the mean of its divisors is an integer number (5252396689755).

Almost surely, 2^{21009571220773} is an apocalyptic number.

It is an amenable number.

21009571220773 is a deficient number, since it is larger than the sum of its proper divisors (15538247).

21009571220773 is a wasteful number, since it uses less digits than its factorization.

21009571220773 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 15538246.

The product of its (nonzero) digits is 370440, while the sum is 46.

The spelling of 21009571220773 in words is "twenty-one trillion, nine billion, five hundred seventy-one million, two hundred twenty thousand, seven hundred seventy-three".