216236681 has 4 divisors (see below), whose sum is σ = 217668864. Its totient is φ = 214804500.

The previous prime is 216236641. The next prime is 216236689. The reversal of 216236681 is 186632612.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-216236681 is a prime.

It is a super-2 number, since 2×216236681² = 93516604419791522, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (216236689) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 715865 + ... + 716166.

It is an arithmetic number, because the mean of its divisors is an integer number (54417216).

Almost surely, 2^216236681 is an apocalyptic number.

It is an amenable number.

216236681 is a deficient number, since it is larger than the sum of its proper divisors (1432183).

216236681 is a wasteful number, since it uses less digits than its factorization.

216236681 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1432182.

The product of its digits is 20736, while the sum is 35.

The square root of 216236681 is about 14704.9883032935. The cubic root of 216236681 is about 600.2190690789.

The spelling of 216236681 in words is "two hundred sixteen million, two hundred thirty-six thousand, six hundred eighty-one".