216431531 has 4 divisors (see below), whose sum is σ = 218532912. Its totient is φ = 214330152.

The previous prime is 216431473. The next prime is 216431533. The reversal of 216431531 is 135134612.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 216431531 - 2²² = 212237227 is a prime.

It is a super-2 number, since 2×216431531² = 93685215222007922, which contains 22 as substring.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 216431531.

It is not an unprimeable number, because it can be changed into a prime (216431533) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1050536 + ... + 1050741.

It is an arithmetic number, because the mean of its divisors is an integer number (54633228).

Almost surely, 2^216431531 is an apocalyptic number.

216431531 is a deficient number, since it is larger than the sum of its proper divisors (2101381).

216431531 is a wasteful number, since it uses less digits than its factorization.

216431531 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2101380.

The product of its digits is 2160, while the sum is 26.

The square root of 216431531 is about 14711.6121142450. The cubic root of 216431531 is about 600.3992999477.

The spelling of 216431531 in words is "two hundred sixteen million, four hundred thirty-one thousand, five hundred thirty-one".