21121206 has 8 divisors (see below), whose sum is σ = 42242424. Its totient is φ = 7040400.

The previous prime is 21121201. The next prime is 21121207. The reversal of 21121206 is 60212112.

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

21121206 is an admirable number.

It is a super-2 number, since 2×21121206² = 892210685788872, which contains 22 as substring.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21121201) 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, 1760095 + ... + 1760106.

It is an arithmetic number, because the mean of its divisors is an integer number (5280303).

Almost surely, 2^21121206 is an apocalyptic number.

21121206 is a primitive abundant number, since it is smaller than the sum of its proper divisors, none of which is abundant.

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21121206 is a wasteful number, since it uses less digits than its factorization.

21121206 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3520206.

The product of its (nonzero) digits is 48, while the sum is 15.

The square root of 21121206 is about 4595.7813263905. The cubic root of 21121206 is about 276.4221904453.

Adding to 21121206 its reverse (60212112), we get a palindrome (81333318).

The spelling of 21121206 in words is "twenty-one million, one hundred twenty-one thousand, two hundred six".