21800017917 has 8 divisors (see below), whose sum is σ = 32296322880. Its totient is φ = 14533345260.

The previous prime is 21800017907. The next prime is 21800017933. The reversal of 21800017917 is 71971000812.

It is not a de Polignac number, because 21800017917 - 2¹⁹ = 21799493629 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21800017907) 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, 403704009 + ... + 403704062.

It is an arithmetic number, because the mean of its divisors is an integer number (4037040360).

Almost surely, 2^21800017917 is an apocalyptic number.

21800017917 is a gapful number since it is divisible by the number (27) formed by its first and last digit.

It is an amenable number.

21800017917 is a deficient number, since it is larger than the sum of its proper divisors (10496304963).

21800017917 is an equidigital number, since it uses as much as digits as its factorization.

21800017917 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 807408080 (or 807408074 counting only the distinct ones).

The product of its (nonzero) digits is 7056, while the sum is 36.

The spelling of 21800017917 in words is "twenty-one billion, eight hundred million, seventeen thousand, nine hundred seventeen".