19400478991 has 4 divisors (see below), whose sum is σ = 19400779312.
Its totient is φ = 19400178672.
The previous prime is 19400478973. The next prime is 19400478997. The reversal of 19400478991 is 19987400491.
It is a semiprime because it is the product of two primes.
It is a cyclic number.
It is not a de Polignac number, because 19400478991 - 25 = 19400478959 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 (19400478997) 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, 9075 + ... + 197188.
It is an arithmetic number, because the mean of its divisors is an integer number (4850194828).
Almost surely, 219400478991 is an apocalyptic number.
19400478991 is a deficient number, since it is larger than the sum of its proper divisors (300321).
19400478991 is an equidigital number, since it uses as much as digits as its factorization.
19400478991 is an evil number, because the sum of its binary digits is even.
The sum of its prime factors is 300320.
The product of its (nonzero) digits is 653184, while the sum is 52.
The spelling of 19400478991 in words is "nineteen billion, four hundred million, four hundred seventy-eight thousand, nine hundred ninety-one".