16660621 has 2 divisors, whose sum is σ = 16660622. Its totient is φ = 16660620.

The previous prime is 16660613. The next prime is 16660639. The reversal of 16660621 is 12606661.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 15515721 + 1144900 = 3939^2 + 1070^2 .

It is an emirp because it is prime and its reverse (12606661) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 16660621 - 2³ = 16660613 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 16660621.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (16660681) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 8330310 + 8330311.

It is an arithmetic number, because the mean of its divisors is an integer number (8330311).

Almost surely, 2^16660621 is an apocalyptic number.

It is an amenable number.

16660621 is a deficient number, since it is larger than the sum of its proper divisors (1).

16660621 is an equidigital number, since it uses as much as digits as its factorization.

16660621 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 2592, while the sum is 28.

The square root of 16660621 is about 4081.7423975552. The cubic root of 16660621 is about 255.4055880533.

The spelling of 16660621 in words is "sixteen million, six hundred sixty thousand, six hundred twenty-one".