21620065 has 8 divisors (see below), whose sum is σ = 25969320. Its totient is φ = 17279232.

The previous prime is 21620063. The next prime is 21620083. The reversal of 21620065 is 56002612.

It can be written as a sum of positive squares in 4 ways, for example, as 13417569 + 8202496 = 3663^2 + 2864^2 .

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 21620065 - 2¹ = 21620063 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21620063) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 7737 + ... + 10153.

It is an arithmetic number, because the mean of its divisors is an integer number (3246165).

Almost surely, 2^21620065 is an apocalyptic number.

It is an amenable number.

21620065 is a deficient number, since it is larger than the sum of its proper divisors (4349255).

21620065 is a wasteful number, since it uses less digits than its factorization.

21620065 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4211.

The product of its (nonzero) digits is 720, while the sum is 22.

The square root of 21620065 is about 4649.7381646712. The cubic root of 21620065 is about 278.5815380320.

Adding to 21620065 its reverse (56002612), we get a palindrome (77622677).

The spelling of 21620065 in words is "twenty-one million, six hundred twenty thousand, sixty-five".