21617653 has 2 divisors, whose sum is σ = 21617654. Its totient is φ = 21617652.

The previous prime is 21617627. The next prime is 21617663. The reversal of 21617653 is 35671612.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 17114769 + 4502884 = 4137^2 + 2122^2 .

It is a cyclic number.

It is not a de Polignac number, because 21617653 - 2⁵ = 21617621 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21617663) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10808826 + 10808827.

It is an arithmetic number, because the mean of its divisors is an integer number (10808827).

Almost surely, 2^21617653 is an apocalyptic number.

It is an amenable number.

21617653 is a deficient number, since it is larger than the sum of its proper divisors (1).

21617653 is an equidigital number, since it uses as much as digits as its factorization.

21617653 is an evil number, because the sum of its binary digits is even.

The product of its digits is 7560, while the sum is 31.

The square root of 21617653 is about 4649.4787879933. The cubic root of 21617653 is about 278.5711778464.

The spelling of 21617653 in words is "twenty-one million, six hundred seventeen thousand, six hundred fifty-three".