21121606 has 16 divisors (see below), whose sum is σ = 34816320. Its totient is φ = 9530280.

The previous prime is 21121603. The next prime is 21121619. The reversal of 21121606 is 60612112.

It is a super-2 number, since 2×21121606² = 892244480038472, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21121603) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 396 + ... + 6511.

It is an arithmetic number, because the mean of its divisors is an integer number (2176020).

Almost surely, 2^21121606 is an apocalyptic number.

21121606 is a deficient number, since it is larger than the sum of its proper divisors (13694714).

21121606 is a wasteful number, since it uses less digits than its factorization.

21121606 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7059.

The product of its (nonzero) digits is 144, while the sum is 19.

The square root of 21121606 is about 4595.8248443560. The cubic root of 21121606 is about 276.4239354242.

Adding to 21121606 its product of nonzero digits (144), we get a triangular number (21121750 = T₆₄₉₉).

Adding to 21121606 its reverse (60612112), we get a palindrome (81733718).

The spelling of 21121606 in words is "twenty-one million, one hundred twenty-one thousand, six hundred six".