21255605 has 8 divisors (see below), whose sum is σ = 29150592. Its totient is φ = 14575248.

The previous prime is 21255587. The next prime is 21255607. The reversal of 21255605 is 50655212.

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 21255605 - 2⁶ = 21255541 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21255607) 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, 303617 + ... + 303686.

It is an arithmetic number, because the mean of its divisors is an integer number (3643824).

Almost surely, 2^21255605 is an apocalyptic number.

It is an amenable number.

21255605 is a deficient number, since it is larger than the sum of its proper divisors (7894987).

21255605 is an equidigital number, since it uses as much as digits as its factorization.

21255605 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 607315.

The product of its (nonzero) digits is 3000, while the sum is 26.

The square root of 21255605 is about 4610.3801361710. The cubic root of 21255605 is about 277.0072634691.

The spelling of 21255605 in words is "twenty-one million, two hundred fifty-five thousand, six hundred five".