21345945 has 16 divisors (see below), whose sum is σ = 34309440. Its totient is φ = 11332544.

The previous prime is 21345923. The next prime is 21345959. The reversal of 21345945 is 54954312.

It is a cyclic number.

It is not a de Polignac number, because 21345945 - 2⁶ = 21345881 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, 271 + ... + 6539.

It is an arithmetic number, because the mean of its divisors is an integer number (2144340).

Almost surely, 2^21345945 is an apocalyptic number.

It is an amenable number.

21345945 is a deficient number, since it is larger than the sum of its proper divisors (12963495).

21345945 is a wasteful number, since it uses less digits than its factorization.

21345945 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6504.

The product of its digits is 21600, while the sum is 33.

The square root of 21345945 is about 4620.1672047665. The cubic root of 21345945 is about 277.3991517320.

The spelling of 21345945 in words is "twenty-one million, three hundred forty-five thousand, nine hundred forty-five".