6531136621 has 2 divisors, whose sum is σ = 6531136622. Its totient is φ = 6531136620.

The previous prime is 6531136561. The next prime is 6531136639. The reversal of 6531136621 is 1266311356.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 4883913225 + 1647223396 = 69885^2 + 40586^2 .

It is a cyclic number.

It is not a de Polignac number, because 6531136621 - 2¹⁵ = 6531103853 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (6531136421) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 3265568310 + 3265568311.

It is an arithmetic number, because the mean of its divisors is an integer number (3265568311).

Almost surely, 2^6531136621 is an apocalyptic number.

It is an amenable number.

6531136621 is a deficient number, since it is larger than the sum of its proper divisors (1).

6531136621 is an equidigital number, since it uses as much as digits as its factorization.

6531136621 is an evil number, because the sum of its binary digits is even.

The product of its digits is 19440, while the sum is 34.

The square root of 6531136621 is about 80815.4479106563. The cubic root of 6531136621 is about 1869.2307760194.

Adding to 6531136621 its reverse (1266311356), we get a palindrome (7797447977).

The spelling of 6531136621 in words is "six billion, five hundred thirty-one million, one hundred thirty-six thousand, six hundred twenty-one".