21665011 has 8 divisors (see below), whose sum is σ = 22927104. Its totient is φ = 20429640.

The previous prime is 21665009. The next prime is 21665041. The reversal of 21665011 is 11056612.

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 21665011 - 2¹ = 21665009 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21665041) 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 7 ways as a sum of consecutive naturals, for example, 5001 + ... + 8266.

It is an arithmetic number, because the mean of its divisors is an integer number (2865888).

Almost surely, 2^21665011 is an apocalyptic number.

21665011 is a deficient number, since it is larger than the sum of its proper divisors (1262093).

21665011 is a wasteful number, since it uses less digits than its factorization.

21665011 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 13361.

The product of its (nonzero) digits is 360, while the sum is 22.

The square root of 21665011 is about 4654.5688307297. The cubic root of 21665011 is about 278.7744523315.

The spelling of 21665011 in words is "twenty-one million, six hundred sixty-five thousand, eleven".