634537991 has 2 divisors, whose sum is σ = 634537992. Its totient is φ = 634537990.

The previous prime is 634537963. The next prime is 634537999. The reversal of 634537991 is 199735436.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 634537991 - 2¹⁴ = 634521607 is a prime.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (634537999) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 317268995 + 317268996.

It is an arithmetic number, because the mean of its divisors is an integer number (317268996).

Almost surely, 2^634537991 is an apocalyptic number.

634537991 is a deficient number, since it is larger than the sum of its proper divisors (1).

634537991 is an equidigital number, since it uses as much as digits as its factorization.

634537991 is an evil number, because the sum of its binary digits is even.

The product of its digits is 612360, while the sum is 47.

The square root of 634537991 is about 25190.0375347080. The cubic root of 634537991 is about 859.3152973550.

The spelling of 634537991 in words is "six hundred thirty-four million, five hundred thirty-seven thousand, nine hundred ninety-one".