216321531 has 8 divisors (see below), whose sum is σ = 291669840. Its totient is φ = 142593792.

The previous prime is 216321487. The next prime is 216321551. The reversal of 216321531 is 135123612.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 216321531 - 2¹⁹ = 215797243 is a prime.

It is a super-2 number, since 2×216321531² = 93590009548367922, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (216321551) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 404830 + ... + 405363.

It is an arithmetic number, because the mean of its divisors is an integer number (36458730).

Almost surely, 2^216321531 is an apocalyptic number.

216321531 is a deficient number, since it is larger than the sum of its proper divisors (75348309).

216321531 is an equidigital number, since it uses as much as digits as its factorization.

216321531 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 810285.

The product of its digits is 1080, while the sum is 24.

The square root of 216321531 is about 14707.8730957267. The cubic root of 216321531 is about 600.2975662883.

The spelling of 216321531 in words is "two hundred sixteen million, three hundred twenty-one thousand, five hundred thirty-one".