16610021 has 2 divisors, whose sum is σ = 16610022. Its totient is φ = 16610020.

The previous prime is 16609993. The next prime is 16610029. The reversal of 16610021 is 12001661.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 14145121 + 2464900 = 3761^2 + 1570^2 .

It is a cyclic number.

It is not a de Polignac number, because 16610021 - 2¹⁴ = 16593637 is a prime.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (16610029) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 8305010 + 8305011.

It is an arithmetic number, because the mean of its divisors is an integer number (8305011).

Almost surely, 2^16610021 is an apocalyptic number.

It is an amenable number.

16610021 is a deficient number, since it is larger than the sum of its proper divisors (1).

16610021 is an equidigital number, since it uses as much as digits as its factorization.

16610021 is an evil number, because the sum of its binary digits is even.

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

The square root of 16610021 is about 4075.5393508099. The cubic root of 16610021 is about 255.1467616021.

Adding to 16610021 its reverse (12001661), we get a palindrome (28611682).

The spelling of 16610021 in words is "sixteen million, six hundred ten thousand, twenty-one".