216778783 has 4 divisors (see below), whose sum is σ = 233454088. Its totient is φ = 200103480.

The previous prime is 216778769. The next prime is 216778787. The reversal of 216778783 is 387877612.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-216778783 is a prime.

It is a super-2 number, since 2×216778783² = 93986081517922178, 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 (216778787) 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, 8337633 + ... + 8337658.

It is an arithmetic number, because the mean of its divisors is an integer number (58363522).

Almost surely, 2^216778783 is an apocalyptic number.

216778783 is a deficient number, since it is larger than the sum of its proper divisors (16675305).

216778783 is a wasteful number, since it uses less digits than its factorization.

216778783 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 16675304.

The product of its digits is 790272, while the sum is 49.

The square root of 216778783 is about 14723.4093538148. The cubic root of 216778783 is about 600.7202304712.

The spelling of 216778783 in words is "two hundred sixteen million, seven hundred seventy-eight thousand, seven hundred eighty-three".