21342645 has 36 divisors (see below), whose sum is σ = 37929060. Its totient is φ = 11100672.

The previous prime is 21342641. The next prime is 21342677. The reversal of 21342645 is 54624312.

21342645 is a `hidden beast` number, since 2 + 13 + 4 + 2 + 645 = 666.

It can be written as a sum of positive squares in 6 ways, for example, as 603729 + 20738916 = 777^2 + 4554^2 .

It is not a de Polignac number, because 21342645 - 2² = 21342641 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21342641) by changing a digit.

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 35 ways as a sum of consecutive naturals, for example, 239761 + ... + 239849.

It is an arithmetic number, because the mean of its divisors is an integer number (1053585).

Almost surely, 2^21342645 is an apocalyptic number.

It is an amenable number.

21342645 is a deficient number, since it is larger than the sum of its proper divisors (16586415).

21342645 is an equidigital number, since it uses as much as digits as its factorization.

21342645 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 246 (or 170 counting only the distinct ones).

The product of its digits is 5760, while the sum is 27.

The square root of 21342645 is about 4619.8100610306. The cubic root of 21342645 is about 277.3848560523.

Adding to 21342645 its reverse (54624312), we get a palindrome (75966957).

The spelling of 21342645 in words is "twenty-one million, three hundred forty-two thousand, six hundred forty-five".