17978947 has 8 divisors (see below), whose sum is σ = 20593152. Its totient is φ = 15376200.

The previous prime is 17978941. The next prime is 17978971. The reversal of 17978947 is 74987971.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 17978947 - 2¹⁹ = 17454659 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 17978894 and 17978903.

It is not an unprimeable number, because it can be changed into a prime (17978941) 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, 822 + ... + 6052.

It is an arithmetic number, because the mean of its divisors is an integer number (2574144).

Almost surely, 2^17978947 is an apocalyptic number.

17978947 is a deficient number, since it is larger than the sum of its proper divisors (2614205).

17978947 is an equidigital number, since it uses as much as digits as its factorization.

17978947 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5729.

The product of its digits is 889056, while the sum is 52.

The square root of 17978947 is about 4240.1588413643. The cubic root of 17978947 is about 261.9719246182.

The spelling of 17978947 in words is "seventeen million, nine hundred seventy-eight thousand, nine hundred forty-seven".