217131540 has 96 divisors (see below), whose sum is σ = 637991424. Its totient is φ = 55111680.

The previous prime is 217131539. The next prime is 217131557. The reversal of 217131540 is 45131712.

It is a super-2 number, since 2×217131540² = 94292211325543200, which contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 217131540.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 103300 + ... + 105380.

It is an arithmetic number, because the mean of its divisors is an integer number (6645744).

Almost surely, 2^217131540 is an apocalyptic number.

217131540 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 217131540, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (318995712).

217131540 is an abundant number, since it is smaller than the sum of its proper divisors (420859884).

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

217131540 is a wasteful number, since it uses less digits than its factorization.

217131540 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2177 (or 2175 counting only the distinct ones).

The product of its (nonzero) digits is 840, while the sum is 24.

The square root of 217131540 is about 14735.3839447773. The cubic root of 217131540 is about 601.0458979918.

The spelling of 217131540 in words is "two hundred seventeen million, one hundred thirty-one thousand, five hundred forty".