217998045 has 54 divisors (see below), whose sum is σ = 396022302. Its totient is φ = 110930400.

The previous prime is 217998037. The next prime is 217998049. The reversal of 217998045 is 540899712.

It can be written as a sum of positive squares in only one way, i.e., 174398436 + 43599609 = 13206^2 + 6603^2 .

It is not a de Polignac number, because 217998045 - 2³ = 217998037 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (45).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (217998049) by changing a digit.

It is a polite number, since it can be written in 53 ways as a sum of consecutive naturals, for example, 3070360 + ... + 3070430.

Almost surely, 2^217998045 is an apocalyptic number.

It is an amenable number.

217998045 is a deficient number, since it is larger than the sum of its proper divisors (178024257).

217998045 is an equidigital number, since it uses as much as digits as its factorization.

217998045 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 215 (or 110 counting only the distinct ones).

The product of its (nonzero) digits is 181440, while the sum is 45.

The square root of 217998045 is about 14764.7568554311. The cubic root of 217998045 is about 601.8443663785.

Multiplying 217998045 by its sum of digits (45), we get a square (9809912025 = 99045²).

217998045 divided by its sum of digits (45) gives a square (4844401 = 2201²).

The spelling of 217998045 in words is "two hundred seventeen million, nine hundred ninety-eight thousand, forty-five".