16638442 has 4 divisors (see below), whose sum is σ = 24957666. Its totient is φ = 8319220.

The previous prime is 16638409. The next prime is 16638443. The reversal of 16638442 is 24483661.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 24483661 = 23 ⋅1064507.

It can be written as a sum of positive squares in only one way, i.e., 15752961 + 885481 = 3969^2 + 941^2 .

It is a junction number, because it is equal to n+sod(n) for n = 16638398 and 16638407.

It is not an unprimeable number, because it can be changed into a prime (16638443) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 4159609 + ... + 4159612.

Almost surely, 2^16638442 is an apocalyptic number.

16638442 is a deficient number, since it is larger than the sum of its proper divisors (8319224).

16638442 is an equidigital number, since it uses as much as digits as its factorization.

16638442 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 8319223.

The product of its digits is 27648, while the sum is 34.

The square root of 16638442 is about 4079.0246383174. The cubic root of 16638442 is about 255.2922038037.

The spelling of 16638442 in words is "sixteen million, six hundred thirty-eight thousand, four hundred forty-two".