7218391866 has 32 divisors (see below), whose sum is σ = 16506771840. Its totient is φ = 2061448896.

The previous prime is 7218391849. The next prime is 7218391907. The reversal of 7218391866 is 6681938127.

It is a super-2 number, since 2×7218391866² (a number of 21 digits) contains 22 as substring.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 55540 + ... + 132368.

It is an arithmetic number, because the mean of its divisors is an integer number (515836620).

Almost surely, 2^7218391866 is an apocalyptic number.

7218391866 is an abundant number, since it is smaller than the sum of its proper divisors (9288379974).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

7218391866 is a wasteful number, since it uses less digits than its factorization.

7218391866 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 79078.

The product of its digits is 870912, while the sum is 51.

The square root of 7218391866 is about 84961.1197313218. The cubic root of 7218391866 is about 1932.6215518993.

The spelling of 7218391866 in words is "seven billion, two hundred eighteen million, three hundred ninety-one thousand, eight hundred sixty-six".