217145380 has 24 divisors (see below), whose sum is σ = 457039800. Its totient is φ = 86661120.

The previous prime is 217145377. The next prime is 217145387. The reversal of 217145380 is 83541712.

It can be written as a sum of positive squares in 4 ways, for example, as 50580544 + 166564836 = 7112^2 + 12906^2 .

It is not an unprimeable number, because it can be changed into a prime (217145387) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 3111 + ... + 21070.

It is an arithmetic number, because the mean of its divisors is an integer number (19043325).

Almost surely, 2^217145380 is an apocalyptic number.

217145380 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

217145380 is an abundant number, since it is smaller than the sum of its proper divisors (239894420).

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

217145380 is a wasteful number, since it uses less digits than its factorization.

217145380 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 24639 (or 24637 counting only the distinct ones).

The product of its (nonzero) digits is 6720, while the sum is 31.

The square root of 217145380 is about 14735.8535551898. The cubic root of 217145380 is about 601.0586679753.

The spelling of 217145380 in words is "two hundred seventeen million, one hundred forty-five thousand, three hundred eighty".