216031021 has 8 divisors (see below), whose sum is σ = 222291864. Its totient is φ = 209851200.

The previous prime is 216031001. The next prime is 216031069. The reversal of 216031021 is 120130612.

It can be written as a sum of positive squares in 4 ways, for example, as 48846121 + 167184900 = 6989^2 + 12930^2 .

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

It is a cyclic number.

It is not a de Polignac number, because 216031021 - 2²⁷ = 81813293 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 216030986 and 216031004.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (216031001) 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, 14826 + ... + 25531.

It is an arithmetic number, because the mean of its divisors is an integer number (27786483).

Almost surely, 2^216031021 is an apocalyptic number.

It is an amenable number.

216031021 is a deficient number, since it is larger than the sum of its proper divisors (6260843).

216031021 is a wasteful number, since it uses less digits than its factorization.

216031021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 40511.

The product of its (nonzero) digits is 72, while the sum is 16.

The square root of 216031021 is about 14697.9937746619. The cubic root of 216031021 is about 600.0287217732.

Adding to 216031021 its reverse (120130612), we get a palindrome (336161633).

The spelling of 216031021 in words is "two hundred sixteen million, thirty-one thousand, twenty-one".