521640001 has 4 divisors (see below), whose sum is σ = 521686404. Its totient is φ = 521593600.

The previous prime is 521639999. The next prime is 521640013. The reversal of 521640001 is 100046125.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It can be written as a sum of positive squares in 2 ways, for example, as 429940225 + 91699776 = 20735^2 + 9576^2 .

It is a cyclic number.

It is not a de Polignac number, because 521640001 - 2¹ = 521639999 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (521640071) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 5481 + ... + 32761.

It is an arithmetic number, because the mean of its divisors is an integer number (130421601).

Almost surely, 2^521640001 is an apocalyptic number.

It is an amenable number.

521640001 is a deficient number, since it is larger than the sum of its proper divisors (46403).

521640001 is a wasteful number, since it uses less digits than its factorization.

521640001 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 46402.

The product of its (nonzero) digits is 240, while the sum is 19.

The square root of 521640001 is about 22839.4395947011. The cubic root of 521640001 is about 804.9896484144.

Adding to 521640001 its reverse (100046125), we get a palindrome (621686126).

The spelling of 521640001 in words is "five hundred twenty-one million, six hundred forty thousand, one".