21642308 has 12 divisors (see below), whose sum is σ = 38300220. Its totient is φ = 10699392.

The previous prime is 21642307. The next prime is 21642317. The reversal of 21642308 is 80324612.

It can be written as a sum of positive squares in 2 ways, for example, as 9684544 + 11957764 = 3112^2 + 3458^2 .

It is not an unprimeable number, because it can be changed into a prime (21642307) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 30041 + ... + 30752.

It is an arithmetic number, because the mean of its divisors is an integer number (3191685).

Almost surely, 2^21642308 is an apocalyptic number.

It is an amenable number.

21642308 is a deficient number, since it is larger than the sum of its proper divisors (16657912).

21642308 is a wasteful number, since it uses less digits than its factorization.

21642308 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 60886 (or 60884 counting only the distinct ones).

The product of its (nonzero) digits is 2304, while the sum is 26.

The square root of 21642308 is about 4652.1294049070. The cubic root of 21642308 is about 278.6770413736.

Adding to 21642308 its product of nonzero digits (2304), we get a palindrome (21644612).

It can be divided in two parts, 216 and 42308, that added together give a palindrome (42524).

The spelling of 21642308 in words is "twenty-one million, six hundred forty-two thousand, three hundred eight".