217664425 has 24 divisors (see below), whose sum is σ = 295418592. Its totient is φ = 157776000.

The previous prime is 217664417. The next prime is 217664431. The reversal of 217664425 is 524466712.

It is not a de Polignac number, because 217664425 - 2³ = 217664417 is a prime.

It is a Duffinian number.

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 94285 + ... + 96565.

It is an arithmetic number, because the mean of its divisors is an integer number (12309108).

Almost surely, 2^217664425 is an apocalyptic number.

217664425 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

It is an amenable number.

217664425 is a deficient number, since it is larger than the sum of its proper divisors (77754167).

217664425 is a wasteful number, since it uses less digits than its factorization.

217664425 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2649 (or 2644 counting only the distinct ones).

The product of its digits is 80640, while the sum is 37.

The square root of 217664425 is about 14753.4546801758. The cubic root of 217664425 is about 601.5371926274.

It can be divided in two parts, 217664 and 425, that added together give a square (218089 = 467²).

The spelling of 217664425 in words is "two hundred seventeen million, six hundred sixty-four thousand, four hundred twenty-five".