633991 has 2 divisors, whose sum is σ = 633992. Its totient is φ = 633990.

The previous prime is 633967. The next prime is 634003. The reversal of 633991 is 199336.

633991 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 633991 - 2¹⁷ = 502919 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (633931) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 316995 + 316996.

It is an arithmetic number, because the mean of its divisors is an integer number (316996).

2⁶³³⁹⁹¹ is an apocalyptic number.

633991 is a deficient number, since it is larger than the sum of its proper divisors (1).

633991 is an equidigital number, since it uses as much as digits as its factorization.

633991 is an evil number, because the sum of its binary digits is even.

The product of its digits is 4374, while the sum is 31.

The square root of 633991 is about 796.2355179217. The cubic root of 633991 is about 85.9068307751.

The spelling of 633991 in words is "six hundred thirty-three thousand, nine hundred ninety-one".