21682207 has 4 divisors (see below), whose sum is σ = 21763080. Its totient is φ = 21601336.

The previous prime is 21682201. The next prime is 21682223. The reversal of 21682207 is 70228612.

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 21682207 - 2⁷ = 21682079 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 (21682201) 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 3 ways as a sum of consecutive naturals, for example, 40033 + ... + 40570.

It is an arithmetic number, because the mean of its divisors is an integer number (5440770).

Almost surely, 2^21682207 is an apocalyptic number.

21682207 is a deficient number, since it is larger than the sum of its proper divisors (80873).

21682207 is an equidigital number, since it uses as much as digits as its factorization.

21682207 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 80872.

The product of its (nonzero) digits is 2688, while the sum is 28.

The square root of 21682207 is about 4656.4156816161. The cubic root of 21682207 is about 278.8481893158.

It can be divided in two parts, 2 and 1682207, that added together give a square (1682209 = 1297²).

The spelling of 21682207 in words is "twenty-one million, six hundred eighty-two thousand, two hundred seven".