19998947 has 4 divisors (see below), whose sum is σ = 20008416. Its totient is φ = 19989480.

The previous prime is 19998943. The next prime is 19998949. The reversal of 19998947 is 74989991.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It is a cyclic number.

It is not a de Polignac number, because 19998947 - 2² = 19998943 is a prime.

It is a super-2 number, since 2×19998947² = 799915762217618, which contains 22 as substring.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 19998892 and 19998901.

It is not an unprimeable number, because it can be changed into a prime (19998943) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 38 + ... + 6324.

It is an arithmetic number, because the mean of its divisors is an integer number (5002104).

Almost surely, 2^19998947 is an apocalyptic number.

19998947 is a deficient number, since it is larger than the sum of its proper divisors (9469).

19998947 is an equidigital number, since it uses as much as digits as its factorization.

19998947 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 9468.

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

The square root of 19998947 is about 4472.0182244709. The cubic root of 19998947 is about 271.4369977730.

The spelling of 19998947 in words is "nineteen million, nine hundred ninety-eight thousand, nine hundred forty-seven".