19978728 has 128 divisors (see below), whose sum is σ = 65664000. Its totient is φ = 4907520.

The previous prime is 19978667. The next prime is 19978733. The reversal of 19978728 is 82787991.

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, 34828 + ... + 35396.

It is an arithmetic number, because the mean of its divisors is an integer number (513000).

Almost surely, 2^19978728 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 19978728, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (32832000).

19978728 is an abundant number, since it is smaller than the sum of its proper divisors (45685272).

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

19978728 is a wasteful number, since it uses less digits than its factorization.

19978728 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 615 (or 611 counting only the distinct ones).

The product of its digits is 508032, while the sum is 51.

The square root of 19978728 is about 4469.7570403770. The cubic root of 19978728 is about 271.3454923682.

It can be divided in two parts, 19978 and 728, that added together give a triangular number (20706 = T₂₀₃).

The spelling of 19978728 in words is "nineteen million, nine hundred seventy-eight thousand, seven hundred twenty-eight".