6506721601 has 6 divisors (see below), whose sum is σ = 6661561650. Its totient is φ = 6355400688.

The previous prime is 6506721569. The next prime is 6506721673. The reversal of 6506721601 is 1061276056.

It is a happy number.

It can be written as a sum of positive squares in only one way, i.e., 4924670976 + 1582050625 = 70176^2 + 39775^2 .

It is not a de Polignac number, because 6506721601 - 2⁵ = 6506721569 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (6506721401) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 1757676 + ... + 1761373.

It is an arithmetic number, because the mean of its divisors is an integer number (1110260275).

Almost surely, 2^6506721601 is an apocalyptic number.

It is an amenable number.

6506721601 is a deficient number, since it is larger than the sum of its proper divisors (154840049).

6506721601 is an equidigital number, since it uses as much as digits as its factorization.

6506721601 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3519135 (or 3519092 counting only the distinct ones).

The product of its (nonzero) digits is 15120, while the sum is 34.

The square root of 6506721601 is about 80664.2523116653. The cubic root of 6506721601 is about 1866.8986504025.

Adding to 6506721601 its reverse (1061276056), we get a palindrome (7567997657).

It can be divided in two parts, 65067 and 21601, that added together give a palindrome (86668).

The spelling of 6506721601 in words is "six billion, five hundred six million, seven hundred twenty-one thousand, six hundred one".