21016451 has 4 divisors (see below), whose sum is σ = 22122600. Its totient is φ = 19910304.

The previous prime is 21016441. The next prime is 21016459. The reversal of 21016451 is 15461012.

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

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21016451 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21016459) 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, 553046 + ... + 553083.

It is an arithmetic number, because the mean of its divisors is an integer number (5530650).

Almost surely, 2^21016451 is an apocalyptic number.

21016451 is a deficient number, since it is larger than the sum of its proper divisors (1106149).

21016451 is a wasteful number, since it uses less digits than its factorization.

21016451 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1106148.

The product of its (nonzero) digits is 240, while the sum is 20.

The square root of 21016451 is about 4584.3702948169. The cubic root of 21016451 is about 275.9644417889.

Adding to 21016451 its reverse (15461012), we get a palindrome (36477463).

It can be divided in two parts, 210 and 16451, that added together give a palindrome (16661).

The spelling of 21016451 in words is "twenty-one million, sixteen thousand, four hundred fifty-one".