16650021 has 16 divisors (see below), whose sum is σ = 23687424. Its totient is φ = 10366464.

The previous prime is 16650001. The next prime is 16650041. The reversal of 16650021 is 12005661.

It is a happy number.

It is an interprime number because it is at equal distance from previous prime (16650001) and next prime (16650041).

It is not a de Polignac number, because 16650021 - 2⁵ = 16649989 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 16650021.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (16650001) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 5796 + ... + 8178.

It is an arithmetic number, because the mean of its divisors is an integer number (1480464).

Almost surely, 2^16650021 is an apocalyptic number.

It is an amenable number.

16650021 is a deficient number, since it is larger than the sum of its proper divisors (7037403).

16650021 is a wasteful number, since it uses less digits than its factorization.

16650021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2540.

The product of its (nonzero) digits is 360, while the sum is 21.

The square root of 16650021 is about 4080.4437258710. The cubic root of 16650021 is about 255.3514109293.

Adding to 16650021 its reverse (12005661), we get a palindrome (28655682).

The spelling of 16650021 in words is "sixteen million, six hundred fifty thousand, twenty-one".