21917720866 has 16 divisors (see below), whose sum is σ = 34832086560. Its totient is φ = 10307824960.

The previous prime is 21917720863. The next prime is 21917720873. The reversal of 21917720866 is 66802771912.

It is not an unprimeable number, because it can be changed into a prime (21917720861) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 144040 + ... + 254131.

It is an arithmetic number, because the mean of its divisors is an integer number (2177005410).

Almost surely, 2^21917720866 is an apocalyptic number.

21917720866 is a deficient number, since it is larger than the sum of its proper divisors (12914365694).

21917720866 is a wasteful number, since it uses less digits than its factorization.

21917720866 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 399809.

The product of its (nonzero) digits is 508032, while the sum is 49.

The spelling of 21917720866 in words is "twenty-one billion, nine hundred seventeen million, seven hundred twenty thousand, eight hundred sixty-six".