21107491 has 8 divisors (see below), whose sum is σ = 22254624. Its totient is φ = 19979520.

The previous prime is 21107483. The next prime is 21107509. The reversal of 21107491 is 19470112.

21107491 = T₂₂₆ + T₂₂₇ + ... + T₅₁₆.

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 21107491 - 2³ = 21107483 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21107291) 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, 2500 + ... + 6961.

It is an arithmetic number, because the mean of its divisors is an integer number (2781828).

Almost surely, 2^21107491 is an apocalyptic number.

21107491 is a deficient number, since it is larger than the sum of its proper divisors (1147133).

21107491 is an equidigital number, since it uses as much as digits as its factorization.

21107491 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 9581.

The product of its (nonzero) digits is 504, while the sum is 25.

The square root of 21107491 is about 4594.2889547785. The cubic root of 21107491 is about 276.3623461475.

The spelling of 21107491 in words is "twenty-one million, one hundred seven thousand, four hundred ninety-one".