19543641994 has 4 divisors (see below), whose sum is σ = 29315462994. Its totient is φ = 9771820996.

The previous prime is 19543641959. The next prime is 19543642009. The reversal of 19543641994 is 49914634591.

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

It can be written as a sum of positive squares in only one way, i.e., 17719070769 + 1824571225 = 133113^2 + 42715^2 .

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 4885910497 + ... + 4885910500.

Almost surely, 2^19543641994 is an apocalyptic number.

19543641994 is a deficient number, since it is larger than the sum of its proper divisors (9771821000).

19543641994 is an equidigital number, since it uses as much as digits as its factorization.

19543641994 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9771820999.

The product of its digits is 4199040, while the sum is 55.

The spelling of 19543641994 in words is "nineteen billion, five hundred forty-three million, six hundred forty-one thousand, nine hundred ninety-four".