217172628 has 54 divisors (see below), whose sum is σ = 558748554. Its totient is φ = 71122848.

The previous prime is 217172623. The next prime is 217172651. The reversal of 217172628 is 826271712.

217172628 is a `hidden beast` number, since 2 + 17 + 17 + 2 + 628 = 666.

217172628 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It can be written as a sum of positive squares in only one way, i.e., 180956304 + 36216324 = 13452^2 + 6018^2 .

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a junction number, because it is equal to n+sod(n) for n = 217172592 and 217172601.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (217172623) by changing a digit.

It is a polite number, since it can be written in 17 ways as a sum of consecutive naturals, for example, 124450 + ... + 126182.

Almost surely, 2^217172628 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 217172628, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (279374277).

217172628 is an abundant number, since it is smaller than the sum of its proper divisors (341575926).

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

217172628 is a wasteful number, since it uses less digits than its factorization.

217172628 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1861 (or 1797 counting only the distinct ones).

The product of its digits is 18816, while the sum is 36.

The square root of 217172628 is about 14736.7780739210. The cubic root of 217172628 is about 601.0838077558.

The spelling of 217172628 in words is "two hundred seventeen million, one hundred seventy-two thousand, six hundred twenty-eight".