21216295393225 has 9 divisors (see below), whose sum is σ = 26308234845543. Its totient is φ = 16973017890120.

The previous prime is 21216295393199. The next prime is 21216295393313. The reversal of 21216295393225 is 52239359261212.

The square root of 21216295393225 is 4606115.

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., 7637866341561 + 13578429051664 = 2763669^2 + 3684892^2 .

It is not a de Polignac number, because 21216295393225 - 2¹⁵ = 21216295360457 is a prime.

It is a super-3 number, since 3×21216295393225³ (a number of 41 digits) contains 333 as substring.

It is a Duffinian number.

It is an unprimeable number.

It is a polite number, since it can be written in 8 ways as a sum of consecutive naturals, for example, 22569964 + ... + 23491186.

Almost surely, 2^{21216295393225} is an apocalyptic number.

21216295393225 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

21216295393225 is the 4606115-th square number.

21216295393225 is the 2303058-th centered octagonal number.

It is an amenable number.

21216295393225 is a deficient number, since it is larger than the sum of its proper divisors (5091939452318).

21216295393225 is an frugal number, since it uses more digits than its factorization.

21216295393225 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1842456 (or 921228 counting only the distinct ones).

The product of its digits is 3499200, while the sum is 52.

The spelling of 21216295393225 in words is "twenty-one trillion, two hundred sixteen billion, two hundred ninety-five million, three hundred ninety-three thousand, two hundred twenty-five".