217540009531 has 16 divisors (see below), whose sum is σ = 248263313760. Its totient is φ = 189152974080.

The previous prime is 217540009483. The next prime is 217540009543. The reversal of 217540009531 is 135900045712.

It is a cyclic number.

It is not a de Polignac number, because 217540009531 - 2¹⁷ = 217539878459 is a prime.

It is a super-2 number, since 2×217540009531² (a number of 23 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (217540009231) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 7021485 + ... + 7052398.

It is an arithmetic number, because the mean of its divisors is an integer number (15516457110).

Almost surely, 2^217540009531 is an apocalyptic number.

217540009531 is a deficient number, since it is larger than the sum of its proper divisors (30723304229).

217540009531 is a wasteful number, since it uses less digits than its factorization.

217540009531 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 14073966.

The product of its (nonzero) digits is 37800, while the sum is 37.

The spelling of 217540009531 in words is "two hundred seventeen billion, five hundred forty million, nine thousand, five hundred thirty-one".