21416261 has 4 divisors (see below), whose sum is σ = 21437472. Its totient is φ = 21395052.

The previous prime is 21416183. The next prime is 21416281. The reversal of 21416261 is 16261412.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21416261 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21416281) 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, 9011 + ... + 11136.

It is an arithmetic number, because the mean of its divisors is an integer number (5359368).

Almost surely, 2^21416261 is an apocalyptic number.

It is an amenable number.

21416261 is a deficient number, since it is larger than the sum of its proper divisors (21211).

21416261 is a wasteful number, since it uses less digits than its factorization.

21416261 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 21210.

The product of its digits is 576, while the sum is 23.

The square root of 21416261 is about 4627.7706295796. The cubic root of 21416261 is about 277.7034127984.

Adding to 21416261 its reverse (16261412), we get a palindrome (37677673).

The spelling of 21416261 in words is "twenty-one million, four hundred sixteen thousand, two hundred sixty-one".