21084091 has 8 divisors (see below), whose sum is σ = 25364480. Its totient is φ = 17120808.

The previous prime is 21084083. The next prime is 21084103. The reversal of 21084091 is 19048012.

It is a happy number.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 21084091 - 2³ = 21084083 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21084691) 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, 79131 + ... + 79396.

It is an arithmetic number, because the mean of its divisors is an integer number (3170560).

Almost surely, 2^21084091 is an apocalyptic number.

21084091 is a deficient number, since it is larger than the sum of its proper divisors (4280389).

21084091 is a wasteful number, since it uses less digits than its factorization.

21084091 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 158553.

The product of its (nonzero) digits is 576, while the sum is 25.

The square root of 21084091 is about 4591.7416085838. The cubic root of 21084091 is about 276.2601822581.

The spelling of 21084091 in words is "twenty-one million, eighty-four thousand, ninety-one".