21016442 has 4 divisors (see below), whose sum is σ = 31524666. Its totient is φ = 10508220.

The previous prime is 21016441. The next prime is 21016459. The reversal of 21016442 is 24461012.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in only one way, i.e., 13623481 + 7392961 = 3691^2 + 2719^2 .

It is not an unprimeable number, because it can be changed into a prime (21016441) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 5254109 + ... + 5254112.

Almost surely, 2^21016442 is an apocalyptic number.

21016442 is a deficient number, since it is larger than the sum of its proper divisors (10508224).

21016442 is a wasteful number, since it uses less digits than its factorization.

21016442 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10508223.

The product of its (nonzero) digits is 384, while the sum is 20.

The square root of 21016442 is about 4584.3693132207. The cubic root of 21016442 is about 275.9644023963.

Adding to 21016442 its reverse (24461012), we get a palindrome (45477454).

The spelling of 21016442 in words is "twenty-one million, sixteen thousand, four hundred forty-two".