21212929 has 8 divisors (see below), whose sum is σ = 21591360. Its totient is φ = 20838000.

The previous prime is 21212909. The next prime is 21212941. The reversal of 21212929 is 92921212.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 21212929 - 2¹¹ = 21210881 is a prime.

It is an alternating number because its digits alternate between even and odd.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21212897 and 21212906.

It is not an unprimeable number, because it can be changed into a prime (21212909) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 13284 + ... + 14794.

It is an arithmetic number, because the mean of its divisors is an integer number (2698920).

Almost surely, 2^21212929 is an apocalyptic number.

It is an amenable number.

21212929 is a deficient number, since it is larger than the sum of its proper divisors (378431).

21212929 is a wasteful number, since it uses less digits than its factorization.

21212929 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1751.

The product of its digits is 1296, while the sum is 28.

The square root of 21212929 is about 4605.7495589752. The cubic root of 21212929 is about 276.8217518922.

It can be divided in two parts, 2121 and 2929, that added together give a triangular number (5050 = T₁₀₀).

The spelling of 21212929 in words is "twenty-one million, two hundred twelve thousand, nine hundred twenty-nine".