19988661 has 16 divisors (see below), whose sum is σ = 33228288. Its totient is φ = 10383600.

The previous prime is 19988653. The next prime is 19988671. The reversal of 19988661 is 16688991.

It is not a de Polignac number, because 19988661 - 2³ = 19988653 is a prime.

19988661 is a strobogrammatic number because it is the same when read upside-down.

It is a self number, because there is not a number n which added to its sum of digits gives 19988661.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (19988671) 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, 43035 + ... + 43496.

It is an arithmetic number, because the mean of its divisors is an integer number (2076768).

Almost surely, 2^19988661 is an apocalyptic number.

19988661 is a gapful number since it is divisible by the number (11) formed by its first and last digit.

It is an amenable number.

19988661 is a deficient number, since it is larger than the sum of its proper divisors (13239627).

19988661 is a wasteful number, since it uses less digits than its factorization.

19988661 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 86552.

The product of its digits is 186624, while the sum is 48.

The square root of 19988661 is about 4470.8680365227. The cubic root of 19988661 is about 271.3904539931.

The spelling of 19988661 in words is "nineteen million, nine hundred eighty-eight thousand, six hundred sixty-one".