21616037 has 4 divisors (see below), whose sum is σ = 21628620. Its totient is φ = 21603456.

The previous prime is 21616031. The next prime is 21616039. The reversal of 21616037 is 73061612.

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

It can be written as a sum of positive squares in 2 ways, for example, as 14508481 + 7107556 = 3809^2 + 2666^2 .

It is a cyclic number.

It is not a de Polignac number, because 21616037 - 2⁶ = 21615973 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21615997 and 21616015.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21616031) 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 3 ways as a sum of consecutive naturals, for example, 3212 + ... + 7317.

It is an arithmetic number, because the mean of its divisors is an integer number (5407155).

Almost surely, 2^21616037 is an apocalyptic number.

It is an amenable number.

21616037 is a deficient number, since it is larger than the sum of its proper divisors (12583).

21616037 is a wasteful number, since it uses less digits than its factorization.

21616037 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 12582.

The product of its (nonzero) digits is 1512, while the sum is 26.

The square root of 21616037 is about 4649.3050018255. The cubic root of 21616037 is about 278.5642362628.

Adding to 21616037 its reverse (73061612), we get a palindrome (94677649).

The spelling of 21616037 in words is "twenty-one million, six hundred sixteen thousand, thirty-seven".