21605506304 has 36 divisors (see below), whose sum is σ = 43553664420. Its totient is φ = 10695782400.

The previous prime is 21605506303. The next prime is 21605506333. The reversal of 21605506304 is 40360550612.

It can be written as a sum of positive squares in 2 ways, for example, as 16294011904 + 5311494400 = 127648^2 + 72880^2 .

It is a Harshad number since it is a multiple of its sum of digits (32).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21605506303) 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, 391949 + ... + 443660.

Almost surely, 2^21605506304 is an apocalyptic number.

It is an amenable number.

21605506304 is an abundant number, since it is smaller than the sum of its proper divisors (21948158116).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21605506304 is an equidigital number, since it uses as much as digits as its factorization.

21605506304 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 835726 (or 835712 counting only the distinct ones).

The product of its (nonzero) digits is 21600, while the sum is 32.

The spelling of 21605506304 in words is "twenty-one billion, six hundred five million, five hundred six thousand, three hundred four".