16628921 has 4 divisors (see below), whose sum is σ = 16722000. Its totient is φ = 16535844.

The previous prime is 16628893. The next prime is 16628951. The reversal of 16628921 is 12982661.

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, and also an emirpimes, since its reverse is a distinct semiprime: 12982661 = 911 ⋅14251.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-16628921 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (16628951) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 46271 + ... + 46628.

It is an arithmetic number, because the mean of its divisors is an integer number (4180500).

Almost surely, 2^16628921 is an apocalyptic number.

It is an amenable number.

16628921 is a deficient number, since it is larger than the sum of its proper divisors (93079).

16628921 is an equidigital number, since it uses as much as digits as its factorization.

16628921 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 93078.

The product of its digits is 10368, while the sum is 35.

The square root of 16628921 is about 4077.8574030979. The cubic root of 16628921 is about 255.2434993067.

The spelling of 16628921 in words is "sixteen million, six hundred twenty-eight thousand, nine hundred twenty-one".