21312242 has 16 divisors (see below), whose sum is σ = 36977472. Its totient is φ = 9023280.

The previous prime is 21312233. The next prime is 21312257. The reversal of 21312242 is 24221312.

It is a self number, because there is not a number n which added to its sum of digits gives 21312242.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 8009 + ... + 10332.

It is an arithmetic number, because the mean of its divisors is an integer number (2311092).

Almost surely, 2^21312242 is an apocalyptic number.

21312242 is a deficient number, since it is larger than the sum of its proper divisors (15665230).

21312242 is a wasteful number, since it uses less digits than its factorization.

21312242 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 18433.

The product of its digits is 192, while the sum is 17.

The square root of 21312242 is about 4616.5183851036. The cubic root of 21312242 is about 277.2530801418.

Adding to 21312242 its reverse (24221312), we get a palindrome (45533554).

The spelling of 21312242 in words is "twenty-one million, three hundred twelve thousand, two hundred forty-two".