16628561 has 2 divisors, whose sum is σ = 16628562. Its totient is φ = 16628560.

The previous prime is 16628551. The next prime is 16628569. The reversal of 16628561 is 16582661.

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., 10601536 + 6027025 = 3256^2 + 2455^2 .

It is a cyclic number.

It is not a de Polignac number, because 16628561 - 2¹⁸ = 16366417 is a prime.

It is a nialpdrome in base 16.

It is not a weakly prime, because it can be changed into another prime (16628569) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 8314280 + 8314281.

It is an arithmetic number, because the mean of its divisors is an integer number (8314281).

Almost surely, 2^16628561 is an apocalyptic number.

It is an amenable number.

16628561 is a deficient number, since it is larger than the sum of its proper divisors (1).

16628561 is an equidigital number, since it uses as much as digits as its factorization.

16628561 is an evil number, because the sum of its binary digits is even.

The product of its digits is 17280, while the sum is 35.

The square root of 16628561 is about 4077.8132620315. The cubic root of 16628561 is about 255.2416573687.

The spelling of 16628561 in words is "sixteen million, six hundred twenty-eight thousand, five hundred sixty-one".