18199564021 has 8 divisors (see below), whose sum is σ = 18444898944. Its totient is φ = 17955859680.

The previous prime is 18199563929. The next prime is 18199564043. The reversal of 18199564021 is 12046599181.

It is a happy number.

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

It is a cyclic number.

It is not a de Polignac number, because 18199564021 - 2¹⁷ = 18199432949 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (18199564051) 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, 385165 + ... + 429826.

It is an arithmetic number, because the mean of its divisors is an integer number (2305612368).

Almost surely, 2^18199564021 is an apocalyptic number.

It is an amenable number.

18199564021 is a deficient number, since it is larger than the sum of its proper divisors (245334923).

18199564021 is a wasteful number, since it uses less digits than its factorization.

18199564021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 815291.

The product of its (nonzero) digits is 155520, while the sum is 46.

It can be divided in two parts, 181995 and 64021, that added together give a square (246016 = 496²).

The spelling of 18199564021 in words is "eighteen billion, one hundred ninety-nine million, five hundred sixty-four thousand, twenty-one".