21605617703 has 2 divisors, whose sum is σ = 21605617704. Its totient is φ = 21605617702.

The previous prime is 21605617699. The next prime is 21605617721. The reversal of 21605617703 is 30771650612.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21605617703 - 2² = 21605617699 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21605617783) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10802808851 + 10802808852.

It is an arithmetic number, because the mean of its divisors is an integer number (10802808852).

Almost surely, 2^21605617703 is an apocalyptic number.

21605617703 is a deficient number, since it is larger than the sum of its proper divisors (1).

21605617703 is an equidigital number, since it uses as much as digits as its factorization.

21605617703 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 52920, while the sum is 38.

The spelling of 21605617703 in words is "twenty-one billion, six hundred five million, six hundred seventeen thousand, seven hundred three".