21605308573 has 8 divisors (see below), whose sum is σ = 21801735288. Its totient is φ = 21408973824.

The previous prime is 21605308567. The next prime is 21605308639. The reversal of 21605308573 is 37580350612.

It can be written as a sum of positive squares in 4 ways, for example, as 304781764 + 21300526809 = 17458^2 + 145947^2 .

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

It is a cyclic number.

It is not a de Polignac number, because 21605308573 - 2⁵ = 21605308541 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 (21605308553) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 503365 + ... + 544597.

It is an arithmetic number, because the mean of its divisors is an integer number (2725216911).

Almost surely, 2^21605308573 is an apocalyptic number.

It is an amenable number.

21605308573 is a deficient number, since it is larger than the sum of its proper divisors (196426715).

21605308573 is a wasteful number, since it uses less digits than its factorization.

21605308573 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 45983.

The product of its (nonzero) digits is 151200, while the sum is 40.

The spelling of 21605308573 in words is "twenty-one billion, six hundred five million, three hundred eight thousand, five hundred seventy-three".