19440643491 has 16 divisors (see below), whose sum is σ = 29027737600. Its totient is φ = 12858376104.

The previous prime is 19440643367. The next prime is 19440643501. The reversal of 19440643491 is 19434604491.

19440643491 is a `hidden beast` number, since 1 + 94 + 40 + 6 + 434 + 91 = 666.

It is not a de Polignac number, because 19440643491 - 2⁷ = 19440643363 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (19440643891) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 2831311 + ... + 2838168.

It is an arithmetic number, because the mean of its divisors is an integer number (1814233600).

Almost surely, 2^19440643491 is an apocalyptic number.

19440643491 is a deficient number, since it is larger than the sum of its proper divisors (9587094109).

19440643491 is a wasteful number, since it uses less digits than its factorization.

19440643491 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5669615 (or 5669609 counting only the distinct ones).

The product of its (nonzero) digits is 373248, while the sum is 45.

The spelling of 19440643491 in words is "nineteen billion, four hundred forty million, six hundred forty-three thousand, four hundred ninety-one".