21009711 has 8 divisors (see below), whose sum is σ = 28215040. Its totient is φ = 13905432.

The previous prime is 21009701. The next prime is 21009719. The reversal of 21009711 is 11790012.

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

It is not a de Polignac number, because 21009711 - 2⁵ = 21009679 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 (21009719) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 24775 + ... + 25608.

It is an arithmetic number, because the mean of its divisors is an integer number (3526880).

Almost surely, 2^21009711 is an apocalyptic number.

21009711 is a deficient number, since it is larger than the sum of its proper divisors (7205329).

21009711 is a wasteful number, since it uses less digits than its factorization.

21009711 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 50525.

The product of its (nonzero) digits is 126, while the sum is 21.

The square root of 21009711 is about 4583.6351294578. The cubic root of 21009711 is about 275.9349379301.

Adding to 21009711 its reverse (11790012), we get a palindrome (32799723).

It can be divided in two parts, 2100 and 9711, that added together give a palindrome (11811).

The spelling of 21009711 in words is "twenty-one million, nine thousand, seven hundred eleven".