19897690639 has 4 divisors (see below), whose sum is σ = 19957804840. Its totient is φ = 19837576440.

The previous prime is 19897690633. The next prime is 19897690649. The reversal of 19897690639 is 93609679891.

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

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-19897690639 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 (19897690633) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 30056604 + ... + 30057265.

It is an arithmetic number, because the mean of its divisors is an integer number (4989451210).

Almost surely, 2^19897690639 is an apocalyptic number.

19897690639 is a deficient number, since it is larger than the sum of its proper divisors (60114201).

19897690639 is an equidigital number, since it uses as much as digits as its factorization.

19897690639 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 60114200.

The product of its (nonzero) digits is 39680928, while the sum is 67.

The spelling of 19897690639 in words is "nineteen billion, eight hundred ninety-seven million, six hundred ninety thousand, six hundred thirty-nine".