21660733 has 4 divisors (see below), whose sum is σ = 22602528. Its totient is φ = 20718940.

The previous prime is 21660713. The next prime is 21660757. The reversal of 21660733 is 33706612.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 21660733 - 2⁵ = 21660701 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 (21660713) 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 3 ways as a sum of consecutive naturals, for example, 470863 + ... + 470908.

It is an arithmetic number, because the mean of its divisors is an integer number (5650632).

Almost surely, 2^21660733 is an apocalyptic number.

21660733 is a gapful number since it is divisible by the number (23) formed by its first and last digit.

It is an amenable number.

21660733 is a deficient number, since it is larger than the sum of its proper divisors (941795).

21660733 is an equidigital number, since it uses as much as digits as its factorization.

21660733 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 941794.

The product of its (nonzero) digits is 4536, while the sum is 28.

The square root of 21660733 is about 4654.1092595684. The cubic root of 21660733 is about 278.7561020737.

The spelling of 21660733 in words is "twenty-one million, six hundred sixty thousand, seven hundred thirty-three".