216691542 has 48 divisors (see below), whose sum is σ = 502632000. Its totient is φ = 67262832.

The previous prime is 216691513. The next prime is 216691589. The reversal of 216691542 is 245196612.

216691542 is a `hidden beast` number, since 21 + 6 + 6 + 91 + 542 = 666.

It is a junction number, because it is equal to n+sod(n) for n = 216691497 and 216691506.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 14809 + ... + 25547.

It is an arithmetic number, because the mean of its divisors is an integer number (10471500).

Almost surely, 2^216691542 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 216691542, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (251316000).

216691542 is an abundant number, since it is smaller than the sum of its proper divisors (285940458).

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

216691542 is a wasteful number, since it uses less digits than its factorization.

216691542 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10825 (or 10822 counting only the distinct ones).

The product of its digits is 25920, while the sum is 36.

The square root of 216691542 is about 14720.4463926880. The cubic root of 216691542 is about 600.6396345371.

The spelling of 216691542 in words is "two hundred sixteen million, six hundred ninety-one thousand, five hundred forty-two".