21416661 has 24 divisors (see below), whose sum is σ = 35530560. Its totient is φ = 12177216.

The previous prime is 21416641. The next prime is 21416669. The reversal of 21416661 is 16661412.

It is not a de Polignac number, because 21416661 - 2⁶ = 21416597 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21416669) by changing a digit.

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 23 ways as a sum of consecutive naturals, for example, 13950 + ... + 15408.

It is an arithmetic number, because the mean of its divisors is an integer number (1480440).

Almost surely, 2^21416661 is an apocalyptic number.

21416661 is a gapful number since it is divisible by the number (21) formed by its first and last digit.

It is an amenable number.

21416661 is a deficient number, since it is larger than the sum of its proper divisors (14113899).

21416661 is a wasteful number, since it uses less digits than its factorization.

21416661 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1705 (or 1702 counting only the distinct ones).

The product of its digits is 1728, while the sum is 27.

The square root of 21416661 is about 4627.8138467315. The cubic root of 21416661 is about 277.7051417132.

The spelling of 21416661 in words is "twenty-one million, four hundred sixteen thousand, six hundred sixty-one".