2216645781 has 24 divisors (see below), whose sum is σ = 3440667744. Its totient is φ = 1265695200.

The previous prime is 2216645779. The next prime is 2216645797. The reversal of 2216645781 is 1875466122.

It is a happy number.

It is not a de Polignac number, because 2216645781 - 2¹ = 2216645779 is a prime.

It is a super-2 number, since 2×2216645781² = 9827037036850199922, which contains 22 as substring.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (2216645381) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 218931 + ... + 228831.

It is an arithmetic number, because the mean of its divisors is an integer number (143361156).

Almost surely, 2^2216645781 is an apocalyptic number.

2216645781 is a gapful number since it is divisible by the number (21) formed by its first and last digit.

It is an amenable number.

2216645781 is a deficient number, since it is larger than the sum of its proper divisors (1224021963).

2216645781 is a wasteful number, since it uses less digits than its factorization.

2216645781 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 11441 (or 11434 counting only the distinct ones).

The product of its digits is 161280, while the sum is 42.

The square root of 2216645781 is about 47081.2678355203. The cubic root of 2216645781 is about 1303.8634146040.

The spelling of 2216645781 in words is "two billion, two hundred sixteen million, six hundred forty-five thousand, seven hundred eighty-one".