16621001 has 4 divisors (see below), whose sum is σ = 16643604. Its totient is φ = 16598400.

The previous prime is 16620983. The next prime is 16621013. The reversal of 16621001 is 10012661.

It is a happy number.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 10012661 = 2753 ⋅3637.

It can be written as a sum of positive squares in 2 ways, for example, as 15376 + 16605625 = 124^2 + 4075^2 .

It is a cyclic number.

It is not a de Polignac number, because 16621001 - 2⁶ = 16620937 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (16621021) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 10160 + ... + 11681.

It is an arithmetic number, because the mean of its divisors is an integer number (4160901).

Almost surely, 2^16621001 is an apocalyptic number.

It is an amenable number.

16621001 is a deficient number, since it is larger than the sum of its proper divisors (22603).

16621001 is an equidigital number, since it uses as much as digits as its factorization.

16621001 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 22602.

The product of its (nonzero) digits is 72, while the sum is 17.

The square root of 16621001 is about 4076.8861892381. The cubic root of 16621001 is about 255.2029705288.

Adding to 16621001 its reverse (10012661), we get a palindrome (26633662).

The spelling of 16621001 in words is "sixteen million, six hundred twenty-one thousand, one".