19881609 has 16 divisors (see below), whose sum is σ = 29593344. Its totient is φ = 11768400.

The previous prime is 19881607. The next prime is 19881629. The reversal of 19881609 is 90618891.

It is not a de Polignac number, because 19881609 - 2¹ = 19881607 is a prime.

It is not an unprimeable number, because it can be changed into a prime (19881607) 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, 5587 + ... + 8424.

It is an arithmetic number, because the mean of its divisors is an integer number (1849584).

Almost surely, 2^19881609 is an apocalyptic number.

It is an amenable number.

19881609 is a deficient number, since it is larger than the sum of its proper divisors (9711735).

19881609 is a wasteful number, since it uses less digits than its factorization.

19881609 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 14068.

The product of its (nonzero) digits is 31104, while the sum is 42.

The square root of 19881609 is about 4458.8797920554. The cubic root of 19881609 is about 270.9050969645.

The spelling of 19881609 in words is "nineteen million, eight hundred eighty-one thousand, six hundred nine".