21720202018 has 8 divisors (see below), whose sum is σ = 33631280640. Its totient is φ = 10509775140.

The previous prime is 21720201991. The next prime is 21720202027. The reversal of 21720202018 is 81020202712.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a junction number, because it is equal to n+sod(n) for n = 21720201983 and 21720202001.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 175162858 + ... + 175162981.

It is an arithmetic number, because the mean of its divisors is an integer number (4203910080).

Almost surely, 2^21720202018 is an apocalyptic number.

21720202018 is a deficient number, since it is larger than the sum of its proper divisors (11911078622).

21720202018 is a wasteful number, since it uses less digits than its factorization.

21720202018 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 350325872.

The product of its (nonzero) digits is 896, while the sum is 25.

The spelling of 21720202018 in words is "twenty-one billion, seven hundred twenty million, two hundred two thousand, eighteen".