21327389521 has 9 divisors (see below), whose sum is σ = 21924939099. Its totient is φ = 20745716184.

The previous prime is 21327389497. The next prime is 21327389563. The reversal of 21327389521 is 12598372312.

The square root of 21327389521 is 146039.

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

It can be written as a sum of positive squares in only one way, i.e., 19084041025 + 2243348496 = 138145^2 + 47364^2 .

It is not a de Polignac number, because 21327389521 - 2¹³ = 21327381329 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21327329521) by changing a digit.

It is a polite number, since it can be written in 8 ways as a sum of consecutive naturals, for example, 5401470 + ... + 5405416.

Almost surely, 2^21327389521 is an apocalyptic number.

21327389521 is the 146039-th square number.

21327389521 is the 73020-th centered octagonal number.

It is an amenable number.

21327389521 is a deficient number, since it is larger than the sum of its proper divisors (597549578).

21327389521 is an frugal number, since it uses more digits than its factorization.

21327389521 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7968 (or 3984 counting only the distinct ones).

The product of its digits is 181440, while the sum is 43.

The spelling of 21327389521 in words is "twenty-one billion, three hundred twenty-seven million, three hundred eighty-nine thousand, five hundred twenty-one".