634039561 has 8 divisors (see below), whose sum is σ = 638231048. Its totient is φ = 629856000.

The previous prime is 634039517. The next prime is 634039579. The reversal of 634039561 is 165930436.

634039561 = T₂₀₅₅₈ + T₂₀₅₅₉ + T₂₀₅₆₀.

It can be written as a sum of positive squares in 4 ways, for example, as 41409225 + 592630336 = 6435^2 + 24344^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a 5-Lehmer number, since φ(634039561) divides (634039561-1)⁵.

It is a cyclic number.

It is not a de Polignac number, because 634039561 - 2²⁹ = 97168649 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 634039561.

It is not an unprimeable number, because it can be changed into a prime (634039501) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 292321 + ... + 294481.

It is an arithmetic number, because the mean of its divisors is an integer number (79778881).

Almost surely, 2^634039561 is an apocalyptic number.

634039561 is the 20560-th centered triangular number.

It is an amenable number.

634039561 is a deficient number, since it is larger than the sum of its proper divisors (4191487).

634039561 is a wasteful number, since it uses less digits than its factorization.

634039561 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3963.

The product of its (nonzero) digits is 58320, while the sum is 37.

The square root of 634039561 is about 25180.1421957859. The cubic root of 634039561 is about 859.0902408445.

Adding to 634039561 its reverse (165930436), we get a palindrome (799969997).

The spelling of 634039561 in words is "six hundred thirty-four million, thirty-nine thousand, five hundred sixty-one".