628557661 has 2 divisors, whose sum is σ = 628557662. Its totient is φ = 628557660.

The previous prime is 628557637. The next prime is 628557673. The reversal of 628557661 is 166755826.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 469545561 + 159012100 = 21669^2 + 12610^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-628557661 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (628527661) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 314278830 + 314278831.

It is an arithmetic number, because the mean of its divisors is an integer number (314278831).

Almost surely, 2^628557661 is an apocalyptic number.

It is an amenable number.

628557661 is a deficient number, since it is larger than the sum of its proper divisors (1).

628557661 is an equidigital number, since it uses as much as digits as its factorization.

628557661 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 604800, while the sum is 46.

The square root of 628557661 is about 25071.0522515510. The cubic root of 628557661 is about 856.6071755047.

The spelling of 628557661 in words is "six hundred twenty-eight million, five hundred fifty-seven thousand, six hundred sixty-one".