21084906 has 16 divisors (see below), whose sum is σ = 43198848. Its totient is φ = 6856800.

The previous prime is 21084887. The next prime is 21084923. The reversal of 21084906 is 60948012.

It is a super-2 number, since 2×21084906² = 889146522057672, which contains 22 as substring.

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, 42610 + ... + 43101.

It is an arithmetic number, because the mean of its divisors is an integer number (2699928).

Almost surely, 2^21084906 is an apocalyptic number.

21084906 is an abundant number, since it is smaller than the sum of its proper divisors (22113942).

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

21084906 is a wasteful number, since it uses less digits than its factorization.

21084906 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 85757.

The product of its (nonzero) digits is 3456, while the sum is 30.

The square root of 21084906 is about 4591.8303540092. The cubic root of 21084906 is about 276.2637418005.

The spelling of 21084906 in words is "twenty-one million, eighty-four thousand, nine hundred six".