19965978 has 48 divisors (see below), whose sum is σ = 46725120. Its totient is φ = 6142752.

The previous prime is 19965961. The next prime is 19965997. The reversal of 19965978 is 87956991.

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 11175 + ... + 12837.

It is an arithmetic number, because the mean of its divisors is an integer number (973440).

Almost surely, 2^19965978 is an apocalyptic number.

19965978 is a gapful number since it is divisible by the number (18) formed by its first and last digit.

It is a practical number, because each smaller number is the sum of distinct divisors of 19965978, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (23362560).

19965978 is an abundant number, since it is smaller than the sum of its proper divisors (26759142).

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

19965978 is a wasteful number, since it uses less digits than its factorization.

19965978 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1723 (or 1720 counting only the distinct ones).

The product of its digits is 1224720, while the sum is 54.

The square root of 19965978 is about 4468.3305607352. The cubic root of 19965978 is about 271.2877577742.

The spelling of 19965978 in words is "nineteen million, nine hundred sixty-five thousand, nine hundred seventy-eight".