19722478 has 4 divisors (see below), whose sum is σ = 29583720. Its totient is φ = 9861238.

The previous prime is 19722473. The next prime is 19722487. The reversal of 19722478 is 87422791.

It is a semiprime because it is the product of two primes.

It is a super-2 number, since 2×19722478² = 777952276920968, which contains 22 as substring.

It is a Smith number, since the sum of its digits (40) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a self number, because there is not a number n which added to its sum of digits gives 19722478.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (19722473) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 4930618 + ... + 4930621.

It is an arithmetic number, because the mean of its divisors is an integer number (7395930).

Almost surely, 2^19722478 is an apocalyptic number.

19722478 is a deficient number, since it is larger than the sum of its proper divisors (9861242).

19722478 is an equidigital number, since it uses as much as digits as its factorization.

19722478 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9861241.

The product of its digits is 56448, while the sum is 40.

The square root of 19722478 is about 4440.9996622382. Note that the first 3 decimals coincide. The cubic root of 19722478 is about 270.1803915676.

The spelling of 19722478 in words is "nineteen million, seven hundred twenty-two thousand, four hundred seventy-eight".