21616601 has 2 divisors, whose sum is σ = 21616602. Its totient is φ = 21616600.

The previous prime is 21616591. The next prime is 21616607. The reversal of 21616601 is 10661612.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 21381376 + 235225 = 4624^2 + 485^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21616601 is a prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (21616607) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10808300 + 10808301.

It is an arithmetic number, because the mean of its divisors is an integer number (10808301).

Almost surely, 2^21616601 is an apocalyptic number.

It is an amenable number.

21616601 is a deficient number, since it is larger than the sum of its proper divisors (1).

21616601 is an equidigital number, since it uses as much as digits as its factorization.

21616601 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 432, while the sum is 23.

The square root of 21616601 is about 4649.3656556567. The cubic root of 21616601 is about 278.5666589835.

The spelling of 21616601 in words is "twenty-one million, six hundred sixteen thousand, six hundred one".