216451997 has 8 divisors (see below), whose sum is σ = 221924472. Its totient is φ = 210988800.

The previous prime is 216451993. The next prime is 216451999. The reversal of 216451997 is 799154612.

It can be written as a sum of positive squares in 4 ways, for example, as 4778596 + 211673401 = 2186^2 + 14549^2 .

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 216451997 - 2² = 216451993 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (216451993) 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 7 ways as a sum of consecutive naturals, for example, 89873 + ... + 92249.

It is an arithmetic number, because the mean of its divisors is an integer number (27740559).

Almost surely, 2^216451997 is an apocalyptic number.

It is an amenable number.

216451997 is a deficient number, since it is larger than the sum of its proper divisors (5472475).

216451997 is a wasteful number, since it uses less digits than its factorization.

216451997 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4639.

The product of its digits is 136080, while the sum is 44.

The square root of 216451997 is about 14712.3076707905. The cubic root of 216451997 is about 600.4182241539.

The spelling of 216451997 in words is "two hundred sixteen million, four hundred fifty-one thousand, nine hundred ninety-seven".