21645342 has 24 divisors (see below), whose sum is σ = 47063016. Its totient is φ = 7189776.

The previous prime is 21645331. The next prime is 21645343. The reversal of 21645342 is 24354612.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21645343) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 3568 + ... + 7484.

It is an arithmetic number, because the mean of its divisors is an integer number (1960959).

Almost surely, 2^21645342 is an apocalyptic number.

21645342 is an abundant number, since it is smaller than the sum of its proper divisors (25417674).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21645342 is a wasteful number, since it uses less digits than its factorization.

21645342 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4232 (or 4229 counting only the distinct ones).

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

The square root of 21645342 is about 4652.4554807112. The cubic root of 21645342 is about 278.6900631923.

Adding to 21645342 its reverse (24354612), we get a palindrome (45999954).

The spelling of 21645342 in words is "twenty-one million, six hundred forty-five thousand, three hundred forty-two".