21606359 has 2 divisors, whose sum is σ = 21606360. Its totient is φ = 21606358.

The previous prime is 21606313. The next prime is 21606419. The reversal of 21606359 is 95360612.

It is a happy number.

It is a weak prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21606359 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21606259) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10803179 + 10803180.

It is an arithmetic number, because the mean of its divisors is an integer number (10803180).

Almost surely, 2^21606359 is an apocalyptic number.

21606359 is a deficient number, since it is larger than the sum of its proper divisors (1).

21606359 is an equidigital number, since it uses as much as digits as its factorization.

21606359 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 9720, while the sum is 32.

The square root of 21606359 is about 4648.2640845804. The cubic root of 21606359 is about 278.5226568384.

The spelling of 21606359 in words is "twenty-one million, six hundred six thousand, three hundred fifty-nine".