216632981 has 8 divisors (see below), whose sum is σ = 219207384. Its totient is φ = 214067200.

The previous prime is 216632957. The next prime is 216633007. The reversal of 216632981 is 189236612.

It is a happy number.

It can be written as a sum of positive squares in 4 ways, for example, as 30747025 + 185885956 = 5545^2 + 13634^2 .

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 216632981 - 2¹⁰ = 216631957 is a prime.

It is a super-2 number, since 2×216632981² = 93859696913892722, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (216632951) 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, 58085 + ... + 61701.

It is an arithmetic number, because the mean of its divisors is an integer number (27400923).

Almost surely, 2^216632981 is an apocalyptic number.

It is an amenable number.

216632981 is a deficient number, since it is larger than the sum of its proper divisors (2574403).

216632981 is a wasteful number, since it uses less digits than its factorization.

216632981 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4311.

The product of its digits is 31104, while the sum is 38.

The square root of 216632981 is about 14718.4571541993. The cubic root of 216632981 is about 600.5855219394.

The spelling of 216632981 in words is "two hundred sixteen million, six hundred thirty-two thousand, nine hundred eighty-one".