216981013 has 4 divisors (see below), whose sum is σ = 229744620. Its totient is φ = 204217408.

The previous prime is 216980983. The next prime is 216981019. The reversal of 216981013 is 310189612.

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

It can be written as a sum of positive squares in 2 ways, for example, as 127735204 + 89245809 = 11302^2 + 9447^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-216981013 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (216981019) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 6381778 + ... + 6381811.

It is an arithmetic number, because the mean of its divisors is an integer number (57436155).

Almost surely, 2^216981013 is an apocalyptic number.

It is an amenable number.

216981013 is a deficient number, since it is larger than the sum of its proper divisors (12763607).

216981013 is a wasteful number, since it uses less digits than its factorization.

216981013 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 12763606.

The product of its (nonzero) digits is 2592, while the sum is 31.

The square root of 216981013 is about 14730.2753877855. The cubic root of 216981013 is about 600.9069736775.

The spelling of 216981013 in words is "two hundred sixteen million, nine hundred eighty-one thousand, thirteen".