21056207 has 4 divisors (see below), whose sum is σ = 21087720. Its totient is φ = 21024696.

The previous prime is 21056179. The next prime is 21056227. The reversal of 21056207 is 70265012.

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

It is a cyclic number.

It is not a de Polignac number, because 21056207 - 2⁶ = 21056143 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21056227) 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, 14732 + ... + 16097.

It is an arithmetic number, because the mean of its divisors is an integer number (5271930).

Almost surely, 2^21056207 is an apocalyptic number.

21056207 is a deficient number, since it is larger than the sum of its proper divisors (31513).

21056207 is an equidigital number, since it uses as much as digits as its factorization.

21056207 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 31512.

The product of its (nonzero) digits is 840, while the sum is 23.

The square root of 21056207 is about 4588.7042833462. The cubic root of 21056207 is about 276.1383425687.

The spelling of 21056207 in words is "twenty-one million, fifty-six thousand, two hundred seven".