21212842 has 16 divisors (see below), whose sum is σ = 36559872. Its totient is φ = 9042480.

The previous prime is 21212837. The next prime is 21212861. The reversal of 21212842 is 24821212.

It is a pancake number, because a pancake can be divided into 21212842 parts by 6513 straight cuts.

It is an unprimeable number.

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 7 ways as a sum of consecutive naturals, for example, 1293 + ... + 6640.

It is an arithmetic number, because the mean of its divisors is an integer number (2284992).

Almost surely, 2^21212842 is an apocalyptic number.

21212842 is a deficient number, since it is larger than the sum of its proper divisors (15347030).

21212842 is a wasteful number, since it uses less digits than its factorization.

21212842 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 8133.

The product of its digits is 512, while the sum is 22.

The square root of 21212842 is about 4605.7401142487. The cubic root of 21212842 is about 276.8213734512.

The spelling of 21212842 in words is "twenty-one million, two hundred twelve thousand, eight hundred forty-two".