19965990 has 64 divisors (see below), whose sum is σ = 55365120. Its totient is φ = 4554240.

The previous prime is 19965961. The next prime is 19965997. The reversal of 19965990 is 9956991.

It is a happy number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (19965997) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 3831 + ... + 7389.

It is an arithmetic number, because the mean of its divisors is an integer number (865080).

Almost surely, 2^19965990 is an apocalyptic number.

19965990 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 19965990, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (27682560).

19965990 is an abundant number, since it is smaller than the sum of its proper divisors (35399130).

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

19965990 is a wasteful number, since it uses less digits than its factorization.

19965990 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3597.

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

The square root of 19965990 is about 4468.3319035184. The cubic root of 19965990 is about 271.2878121242.

The spelling of 19965990 in words is "nineteen million, nine hundred sixty-five thousand, nine hundred ninety".