21355345 has 16 divisors (see below), whose sum is σ = 28434240. Its totient is φ = 15265600.

The previous prime is 21355291. The next prime is 21355351. The reversal of 21355345 is 54355312.

It is not a de Polignac number, because 21355345 - 2²¹ = 19258193 is a prime.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 46 + ... + 6535.

It is an arithmetic number, because the mean of its divisors is an integer number (1777140).

Almost surely, 2^21355345 is an apocalyptic number.

It is an amenable number.

21355345 is a deficient number, since it is larger than the sum of its proper divisors (7078895).

21355345 is a wasteful number, since it uses less digits than its factorization.

21355345 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6656.

The product of its digits is 9000, while the sum is 28.

The square root of 21355345 is about 4621.1843719982. The cubic root of 21355345 is about 277.4398646849.

The spelling of 21355345 in words is "twenty-one million, three hundred fifty-five thousand, three hundred forty-five".