21061628 is an admirable number.
It is a congruent number.
It is an unprimeable number.
Almost surely, 221061628 is an apocalyptic number.
21061628 is a gapful number since it is divisible by the number (28) formed by its first and last digit.
It is an amenable number.
21061628 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.
21061628 is a wasteful number, since it uses less digits than its factorization.
21061628 is an odious number, because the sum of its binary digits is odd.
The square root of 21061628 is about 4589.2949349546. The cubic root of 21061628 is about 276.1620381550.
The spelling of 21061628 in words is "twenty-one million, sixty-one thousand, six hundred twenty-eight".