217384400025 has 135 divisors (see below), whose sum is σ = 436576193031. Its totient is φ = 106885733760.

The previous prime is 217384400011. The next prime is 217384400053. The reversal of 217384400025 is 520004483712.

It is a happy number.

The square root of 217384400025 is 466245.

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

217384400025 is a `hidden beast` number, since 2 + 173 + 84 + 400 + 0 + 2 + 5 = 666.

It can be written as a sum of positive squares in 13 ways, for example, as 205320453129 + 12063946896 = 453123^2 + 109836^2 .

It is a tau number, because it is divible by the number of its divisors (135).

It is not a de Polignac number, because 217384400025 - 2⁵ = 217384399993 is a prime.

It is an unprimeable number.

It is a polite number, since it can be written in 134 ways as a sum of consecutive naturals, for example, 272752927 + ... + 272753723.

Almost surely, 2^217384400025 is an apocalyptic number.

217384400025 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

217384400025 is the 466245-th square number.

217384400025 is the 233123-rd centered octagonal number.

It is an amenable number.

217384400025 is an abundant number, since it is smaller than the sum of its proper divisors (219191793006).

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

217384400025 is an frugal number, since it uses more digits than its factorization.

217384400025 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1642 (or 818 counting only the distinct ones).

The product of its (nonzero) digits is 53760, while the sum is 36.

Multiplying 217384400025 by its sum of digits (36), we get a square (7825838400900 = 2797470²).

Adding to 217384400025 its reverse (520004483712), we get a palindrome (737388883737).

The spelling of 217384400025 in words is "two hundred seventeen billion, three hundred eighty-four million, four hundred thousand, twenty-five".