16639657 has 2 divisors, whose sum is σ = 16639658. Its totient is φ = 16639656.

The previous prime is 16639639. The next prime is 16639673. The reversal of 16639657 is 75693661.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 8737936 + 7901721 = 2956^2 + 2811^2 .

It is a cyclic number.

It is not a de Polignac number, because 16639657 - 2¹⁹ = 16115369 is a prime.

It is not a weakly prime, because it can be changed into another prime (16639607) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 8319828 + 8319829.

It is an arithmetic number, because the mean of its divisors is an integer number (8319829).

Almost surely, 2^16639657 is an apocalyptic number.

It is an amenable number.

16639657 is a deficient number, since it is larger than the sum of its proper divisors (1).

16639657 is an equidigital number, since it uses as much as digits as its factorization.

16639657 is an evil number, because the sum of its binary digits is even.

The product of its digits is 204120, while the sum is 43.

The square root of 16639657 is about 4079.1735682611. The cubic root of 16639657 is about 255.2984177765.

The spelling of 16639657 in words is "sixteen million, six hundred thirty-nine thousand, six hundred fifty-seven".