21395389015225 has 9 divisors (see below), whose sum is σ = 26530311057103. Its totient is φ = 17116292710120.

The previous prime is 21395389015223. The next prime is 21395389015283. The reversal of 21395389015225 is 52251098359312.

The square root of 21395389015225 is 4625515.

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., 7702340045481 + 13693048969744 = 2775309^2 + 3700412^2 .

It is not a de Polignac number, because 21395389015225 - 2¹ = 21395389015223 is a prime.

It is a super-2 number, since 2×21395389015225² (a number of 27 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21395389015223) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 8 ways as a sum of consecutive naturals, for example, 22665024 + ... + 23590126.

Almost surely, 2^{21395389015225} is an apocalyptic number.

21395389015225 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

21395389015225 is the 4625515-th square number.

21395389015225 is the 2312758-th centered octagonal number.

It is an amenable number.

21395389015225 is a deficient number, since it is larger than the sum of its proper divisors (5134922041878).

21395389015225 is an frugal number, since it uses more digits than its factorization.

21395389015225 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1850216 (or 925108 counting only the distinct ones).

The product of its (nonzero) digits is 5832000, while the sum is 55.

The spelling of 21395389015225 in words is "twenty-one trillion, three hundred ninety-five billion, three hundred eighty-nine million, fifteen thousand, two hundred twenty-five".