21016042 has 4 divisors (see below), whose sum is σ = 31524066. Its totient is φ = 10508020.

The previous prime is 21016031. The next prime is 21016049. The reversal of 21016042 is 24061012.

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., 11350161 + 9665881 = 3369^2 + 3109^2 .

It is not an unprimeable number, because it can be changed into a prime (21016049) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 5254009 + ... + 5254012.

Almost surely, 2^21016042 is an apocalyptic number.

21016042 is a deficient number, since it is larger than the sum of its proper divisors (10508024).

21016042 is a wasteful number, since it uses less digits than its factorization.

21016042 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10508023.

The product of its (nonzero) digits is 96, while the sum is 16.

The square root of 21016042 is about 4584.3256865105. The cubic root of 21016042 is about 275.9626516010.

Adding to 21016042 its reverse (24061012), we get a palindrome (45077054).

The spelling of 21016042 in words is "twenty-one million, sixteen thousand, forty-two".