19999478 has 4 divisors (see below), whose sum is σ = 29999220. Its totient is φ = 9999738.

The previous prime is 19999471. The next prime is 19999481. The reversal of 19999478 is 87499991.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 87499991 = 397 ⋅220403.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (19999471) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 4999868 + ... + 4999871.

It is an arithmetic number, because the mean of its divisors is an integer number (7499805).

Almost surely, 2^19999478 is an apocalyptic number.

19999478 is a deficient number, since it is larger than the sum of its proper divisors (9999742).

19999478 is an equidigital number, since it uses as much as digits as its factorization.

19999478 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 9999741.

The product of its digits is 1469664, while the sum is 56.

The square root of 19999478 is about 4472.0775932446. The cubic root of 19999478 is about 271.4394000956.

The spelling of 19999478 in words is "nineteen million, nine hundred ninety-nine thousand, four hundred seventy-eight".