999998642 has 4 divisors (see below), whose sum is σ = 1499997966. Its totient is φ = 499999320.

The previous prime is 999998641. The next prime is 999998653. The reversal of 999998642 is 246899999.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 246899999 = 6857 ⋅36007.

It can be written as a sum of positive squares in only one way, i.e., 953636161 + 46362481 = 30881^2 + 6809^2 .

It is a nialpdrome in base 10.

It is not an unprimeable number, because it can be changed into a prime (999998641) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 249999659 + ... + 249999662.

Almost surely, 2^999998642 is an apocalyptic number.

999998642 is a deficient number, since it is larger than the sum of its proper divisors (499999324).

999998642 is a wasteful number, since it uses less digits than its factorization.

999998642 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 499999323.

The product of its digits is 22674816, while the sum is 65.

The square root of 999998642 is about 31622.7551298112. The cubic root of 999998642 is about 999.9995473331. Note that the first 3 decimals are identical.

The spelling of 999998642 in words is "nine hundred ninety-nine million, nine hundred ninety-eight thousand, six hundred forty-two".