628851991 has 2 divisors, whose sum is σ = 628851992. Its totient is φ = 628851990.

The previous prime is 628851961. The next prime is 628851997. The reversal of 628851991 is 199158826.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 628851991 - 2¹¹ = 628849943 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (628851997) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 314425995 + 314425996.

It is an arithmetic number, because the mean of its divisors is an integer number (314425996).

Almost surely, 2^628851991 is an apocalyptic number.

628851991 is a deficient number, since it is larger than the sum of its proper divisors (1).

628851991 is an equidigital number, since it uses as much as digits as its factorization.

628851991 is an evil number, because the sum of its binary digits is even.

The product of its digits is 311040, while the sum is 49.

The square root of 628851991 is about 25076.9214817130. The cubic root of 628851991 is about 856.7408603212.

The spelling of 628851991 in words is "six hundred twenty-eight million, eight hundred fifty-one thousand, nine hundred ninety-one".