19439947 has 4 divisors (see below), whose sum is σ = 20110320. Its totient is φ = 18769576.

The previous prime is 19439941. The next prime is 19439951. The reversal of 19439947 is 74993491.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 74993491 = 809 ⋅92699.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-19439947 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 19439897 and 19439906.

It is not an unprimeable number, because it can be changed into a prime (19439941) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 335143 + ... + 335200.

It is an arithmetic number, because the mean of its divisors is an integer number (5027580).

Almost surely, 2^19439947 is an apocalyptic number.

19439947 is a deficient number, since it is larger than the sum of its proper divisors (670373).

19439947 is an equidigital number, since it uses as much as digits as its factorization.

19439947 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 670372.

The product of its digits is 244944, while the sum is 46.

The square root of 19439947 is about 4409.0755266836. The cubic root of 19439947 is about 268.8840404368.

The spelling of 19439947 in words is "nineteen million, four hundred thirty-nine thousand, nine hundred forty-seven".