19778642 has 16 divisors (see below), whose sum is σ = 32199552. Its totient is φ = 9057360.

The previous prime is 19778641. The next prime is 19778657. The reversal of 19778642 is 24687791.

It is a junction number, because it is equal to n+sod(n) for n = 19778593 and 19778602.

It is not an unprimeable number, because it can be changed into a prime (19778641) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 503 + ... + 6309.

It is an arithmetic number, because the mean of its divisors is an integer number (2012472).

Almost surely, 2^19778642 is an apocalyptic number.

19778642 is a deficient number, since it is larger than the sum of its proper divisors (12420910).

19778642 is a wasteful number, since it uses less digits than its factorization.

19778642 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5953.

The product of its digits is 169344, while the sum is 44.

The square root of 19778642 is about 4447.3185179386. The cubic root of 19778642 is about 270.4366141058.

The spelling of 19778642 in words is "nineteen million, seven hundred seventy-eight thousand, six hundred forty-two".