21065611 has 4 divisors (see below), whose sum is σ = 24074992. Its totient is φ = 18056232.

The previous prime is 21065609. The next prime is 21065621. The reversal of 21065611 is 11656012.

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 21065611 - 2¹ = 21065609 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21065621) 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, 1504680 + ... + 1504693.

It is an arithmetic number, because the mean of its divisors is an integer number (6018748).

Almost surely, 2^21065611 is an apocalyptic number.

21065611 is a deficient number, since it is larger than the sum of its proper divisors (3009381).

21065611 is an equidigital number, since it uses as much as digits as its factorization.

21065611 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3009380.

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

The square root of 21065611 is about 4589.7288590940. The cubic root of 21065611 is about 276.1794455473.

The spelling of 21065611 in words is "twenty-one million, sixty-five thousand, six hundred eleven".