217961001 has 6 divisors (see below), whose sum is σ = 314832570. Its totient is φ = 145307328.

The previous prime is 217960999. The next prime is 217961011. The reversal of 217961001 is 100169712.

It can be written as a sum of positive squares in only one way, i.e., 215384976 + 2576025 = 14676^2 + 1605^2 .

It is not a de Polignac number, because 217961001 - 2¹ = 217960999 is a prime.

It is not an unprimeable number, because it can be changed into a prime (217961011) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 12108936 + ... + 12108953.

It is an arithmetic number, because the mean of its divisors is an integer number (52472095).

Almost surely, 2^217961001 is an apocalyptic number.

It is an amenable number.

217961001 is a deficient number, since it is larger than the sum of its proper divisors (96871569).

217961001 is a wasteful number, since it uses less digits than its factorization.

217961001 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 24217895 (or 24217892 counting only the distinct ones).

The product of its (nonzero) digits is 756, while the sum is 27.

The square root of 217961001 is about 14763.5023283772. The cubic root of 217961001 is about 601.8102743516.

The spelling of 217961001 in words is "two hundred seventeen million, nine hundred sixty-one thousand, one".