21716045 has 8 divisors (see below), whose sum is σ = 28063896. Its totient is φ = 16036416.

The previous prime is 21716033. The next prime is 21716047. The reversal of 21716045 is 54061712.

It can be written as a sum of positive squares in 4 ways, for example, as 5248681 + 16467364 = 2291^2 + 4058^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 21716045 - 2⁴ = 21716029 is a prime.

It is a super-2 number, since 2×21716045² = 943173220884050, which contains 22 as substring.

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 (21716047) 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 in 7 ways as a sum of consecutive naturals, for example, 166982 + ... + 167111.

It is an arithmetic number, because the mean of its divisors is an integer number (3507987).

Almost surely, 2^21716045 is an apocalyptic number.

It is an amenable number.

21716045 is a deficient number, since it is larger than the sum of its proper divisors (6347851).

21716045 is a wasteful number, since it uses less digits than its factorization.

21716045 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 334111.

The product of its (nonzero) digits is 1680, while the sum is 26.

The square root of 21716045 is about 4660.0477465365. The cubic root of 21716045 is about 278.9931739529.

Adding to 21716045 its reverse (54061712), we get a palindrome (75777757).

The spelling of 21716045 in words is "twenty-one million, seven hundred sixteen thousand, forty-five".