19978644 has 48 divisors (see below), whose sum is σ = 54585216. Its totient is φ = 5568000.

The previous prime is 19978643. The next prime is 19978649. The reversal of 19978644 is 44687991.

It is a junction number, because it is equal to n+sod(n) for n = 19978593 and 19978602.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (19978643) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 544 + ... + 6344.

It is an arithmetic number, because the mean of its divisors is an integer number (1137192).

Almost surely, 2^19978644 is an apocalyptic number.

19978644 is a gapful number since it is divisible by the number (14) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 19978644, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (27292608).

19978644 is an abundant number, since it is smaller than the sum of its proper divisors (34606572).

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

19978644 is a wasteful number, since it uses less digits than its factorization.

19978644 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5856 (or 5854 counting only the distinct ones).

The product of its digits is 435456, while the sum is 48.

The square root of 19978644 is about 4469.7476438833. The cubic root of 19978644 is about 271.3451120795.

The spelling of 19978644 in words is "nineteen million, nine hundred seventy-eight thousand, six hundred forty-four".