216455681 has 16 divisors (see below), whose sum is σ = 243326160. Its totient is φ = 191170560.

The previous prime is 216455651. The next prime is 216455699. The reversal of 216455681 is 186554612.

It is a happy number.

It can be written as a sum of positive squares in 8 ways, for example, as 92467456 + 123988225 = 9616^2 + 11135^2 .

It is a cyclic number.

It is not a de Polignac number, because 216455681 - 2²⁶ = 149346817 is a prime.

It is a super-2 number, since 2×216455681² = 93706123674347522, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (216455621) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 40061 + ... + 45141.

It is an arithmetic number, because the mean of its divisors is an integer number (15207885).

Almost surely, 2^216455681 is an apocalyptic number.

It is an amenable number.

216455681 is a deficient number, since it is larger than the sum of its proper divisors (26870479).

216455681 is a wasteful number, since it uses less digits than its factorization.

216455681 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5236.

The product of its digits is 57600, while the sum is 38.

The square root of 216455681 is about 14712.4328715546. The cubic root of 216455681 is about 600.4216304953.

The spelling of 216455681 in words is "two hundred sixteen million, four hundred fifty-five thousand, six hundred eighty-one".