19659990 has 64 divisors (see below), whose sum is σ = 57106944. Its totient is φ = 4228608.

The previous prime is 19659989. The next prime is 19660001. The reversal of 19659990 is 9995691.

It is a happy number.

It is a Curzon number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 817 + ... + 6323.

It is an arithmetic number, because the mean of its divisors is an integer number (892296).

Almost surely, 2^19659990 is an apocalyptic number.

19659990 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is a practical number, because each smaller number is the sum of distinct divisors of 19659990, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (28553472).

19659990 is an abundant number, since it is smaller than the sum of its proper divisors (37446954).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

19659990 is a wasteful number, since it uses less digits than its factorization.

19659990 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5541.

The product of its (nonzero) digits is 196830, while the sum is 48.

The square root of 19659990 is about 4433.9587278187. The cubic root of 19659990 is about 269.8947463545.

The spelling of 19659990 in words is "nineteen million, six hundred fifty-nine thousand, nine hundred ninety".