21306551273604 has 135 divisors (see below), whose sum is σ = 56278640134101. Its totient is φ = 7029095565600.

The previous prime is 21306551273597. The next prime is 21306551273627. The reversal of 21306551273604 is 40637215560312.

The square root of 21306551273604 is 4615902.

It is a perfect power (a square), and thus also a powerful number.

21306551273604 is a `hidden beast` number, since 2 + 1 + 3 + 0 + 6 + 5 + 512 + 73 + 60 + 4 = 666.

It can be written as a sum of positive squares in only one way, i.e., 20471082152004 + 835469121600 = 4524498^2 + 914040^2 .

It is a self number, because there is not a number n which added to its sum of digits gives 21306551273604.

It is an unprimeable number.

It is a polite number, since it can be written in 44 ways as a sum of consecutive naturals, for example, 8391708567 + ... + 8391711105.

Almost surely, 2^{21306551273604} is an apocalyptic number.

21306551273604 is the 4615902-nd square number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21306551273604

21306551273604 is an abundant number, since it is smaller than the sum of its proper divisors (34972088860497).

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

21306551273604 is an frugal number, since it uses more digits than its factorization.

21306551273604 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5296 (or 2645 counting only the distinct ones).

The product of its (nonzero) digits is 907200, while the sum is 45.

The spelling of 21306551273604 in words is "twenty-one trillion, three hundred six billion, five hundred fifty-one million, two hundred seventy-three thousand, six hundred four".