18919920001 has 4 divisors (see below), whose sum is σ = 18920494404. Its totient is φ = 18919345600.

The previous prime is 18919919999. The next prime is 18919920023. The reversal of 18919920001 is 10002991981.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 12193459776 + 6726460225 = 110424^2 + 82015^2 .

It is a cyclic number.

It is not a de Polignac number, because 18919920001 - 2¹ = 18919919999 is a prime.

It is a Smith number, since the sum of its digits (40) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (18919920091) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 234580 + ... + 304741.

It is an arithmetic number, because the mean of its divisors is an integer number (4730123601).

Almost surely, 2^18919920001 is an apocalyptic number.

It is an amenable number.

18919920001 is a deficient number, since it is larger than the sum of its proper divisors (574403).

18919920001 is an equidigital number, since it uses as much as digits as its factorization.

18919920001 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 574402.

The product of its (nonzero) digits is 11664, while the sum is 40.

The spelling of 18919920001 in words is "eighteen billion, nine hundred nineteen million, nine hundred twenty thousand, one".