634581691 has 2 divisors, whose sum is σ = 634581692. Its totient is φ = 634581690.

The previous prime is 634581677. The next prime is 634581743. The reversal of 634581691 is 196185436.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 634581691 - 2²³ = 626193083 is a prime.

It is not a weakly prime, because it can be changed into another prime (634581601) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 317290845 + 317290846.

It is an arithmetic number, because the mean of its divisors is an integer number (317290846).

Almost surely, 2^634581691 is an apocalyptic number.

634581691 is a deficient number, since it is larger than the sum of its proper divisors (1).

634581691 is an equidigital number, since it uses as much as digits as its factorization.

634581691 is an evil number, because the sum of its binary digits is even.

The product of its digits is 155520, while the sum is 43.

The square root of 634581691 is about 25190.9049261832. The cubic root of 634581691 is about 859.3350236320.

The spelling of 634581691 in words is "six hundred thirty-four million, five hundred eighty-one thousand, six hundred ninety-one".