21012442 has 32 divisors (see below), whose sum is σ = 38335680. Its totient is φ = 8513280.

The previous prime is 21012421. The next prime is 21012449. The reversal of 21012442 is 24421012.

It is not an unprimeable number, because it can be changed into a prime (21012449) 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 15 ways as a sum of consecutive naturals, for example, 5628 + ... + 8584.

It is an arithmetic number, because the mean of its divisors is an integer number (1197990).

Almost surely, 2^21012442 is an apocalyptic number.

21012442 is a gapful number since it is divisible by the number (22) formed by its first and last digit.

21012442 is a deficient number, since it is larger than the sum of its proper divisors (17323238).

21012442 is a wasteful number, since it uses less digits than its factorization.

21012442 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3006.

The product of its (nonzero) digits is 128, while the sum is 16.

The square root of 21012442 is about 4583.9330274340. The cubic root of 21012442 is about 275.9468934439.

Adding to 21012442 its reverse (24421012), we get a palindrome (45433454).

The spelling of 21012442 in words is "twenty-one million, twelve thousand, four hundred forty-two".