19747773649 has 4 divisors (see below), whose sum is σ = 19753748464. Its totient is φ = 19741798836.

The previous prime is 19747773623. The next prime is 19747773653. The reversal of 19747773649 is 94637774791.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 19747773649 - 2²⁷ = 19613555921 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (19747773679) 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, 2982447 + ... + 2989060.

It is an arithmetic number, because the mean of its divisors is an integer number (4938437116).

Almost surely, 2^19747773649 is an apocalyptic number.

It is an amenable number.

19747773649 is a deficient number, since it is larger than the sum of its proper divisors (5974815).

19747773649 is an equidigital number, since it uses as much as digits as its factorization.

19747773649 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5974814.

The product of its digits is 56010528, while the sum is 64.

The spelling of 19747773649 in words is "nineteen billion, seven hundred forty-seven million, seven hundred seventy-three thousand, six hundred forty-nine".