217640725 has 12 divisors (see below), whose sum is σ = 284079040. Its totient is φ = 164948400.

The previous prime is 217640719. The next prime is 217640729. The reversal of 217640725 is 527046712.

It is not a de Polignac number, because 217640725 - 2¹⁷ = 217509653 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (217640729) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 228621 + ... + 229570.

Almost surely, 2^217640725 is an apocalyptic number.

217640725 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

It is an amenable number.

217640725 is a deficient number, since it is larger than the sum of its proper divisors (66438315).

217640725 is a wasteful number, since it uses less digits than its factorization.

217640725 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 458220 (or 458215 counting only the distinct ones).

The product of its (nonzero) digits is 23520, while the sum is 34.

The square root of 217640725 is about 14752.6514566026. The cubic root of 217640725 is about 601.5153594026.

The spelling of 217640725 in words is "two hundred seventeen million, six hundred forty thousand, seven hundred twenty-five".