21091746 has 16 divisors (see below), whose sum is σ = 45428544. Its totient is φ = 6489744.

The previous prime is 21091727. The next prime is 21091751. The reversal of 21091746 is 64719012.

It is a happy number.

It is an unprimeable number.

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, 135126 + ... + 135281.

It is an arithmetic number, because the mean of its divisors is an integer number (2839284).

Almost surely, 2^21091746 is an apocalyptic number.

21091746 is a gapful number since it is divisible by the number (26) formed by its first and last digit.

21091746 is an abundant number, since it is smaller than the sum of its proper divisors (24336798).

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

21091746 is a wasteful number, since it uses less digits than its factorization.

21091746 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 270425.

The product of its (nonzero) digits is 3024, while the sum is 30.

The square root of 21091746 is about 4592.5750946501. The cubic root of 21091746 is about 276.2936121368.

The spelling of 21091746 in words is "twenty-one million, ninety-one thousand, seven hundred forty-six".