21085707 has 4 divisors (see below), whose sum is σ = 28114280. Its totient is φ = 14057136.

The previous prime is 21085703. The next prime is 21085709. The reversal of 21085707 is 70758012.

It is a happy number.

It is a semiprime because it is the product of two primes.

It is not a de Polignac number, because 21085707 - 2² = 21085703 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21085703) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 3514282 + ... + 3514287.

It is an arithmetic number, because the mean of its divisors is an integer number (7028570).

Almost surely, 2^21085707 is an apocalyptic number.

21085707 is a deficient number, since it is larger than the sum of its proper divisors (7028573).

21085707 is an equidigital number, since it uses as much as digits as its factorization.

21085707 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7028572.

The product of its (nonzero) digits is 3920, while the sum is 30.

The square root of 21085707 is about 4591.9175733020. The cubic root of 21085707 is about 276.2672401080.

The spelling of 21085707 in words is "twenty-one million, eighty-five thousand, seven hundred seven".