6561275381 has 2 divisors, whose sum is σ = 6561275382. Its totient is φ = 6561275380.

The previous prime is 6561275321. The next prime is 6561275411. The reversal of 6561275381 is 1835721656.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 6042574756 + 518700625 = 77734^2 + 22775^2 .

It is a cyclic number.

It is not a de Polignac number, because 6561275381 - 2²⁶ = 6494166517 is a prime.

It is a super-2 number, since 2×6561275381² = 86100669250633390322, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (6561275321) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 3280637690 + 3280637691.

It is an arithmetic number, because the mean of its divisors is an integer number (3280637691).

Almost surely, 2^6561275381 is an apocalyptic number.

It is an amenable number.

6561275381 is a deficient number, since it is larger than the sum of its proper divisors (1).

6561275381 is an equidigital number, since it uses as much as digits as its factorization.

6561275381 is an evil number, because the sum of its binary digits is even.

The product of its digits is 302400, while the sum is 44.

The square root of 6561275381 is about 81001.6998648794. The cubic root of 6561275381 is about 1872.1016322213.

It can be divided in two parts, 6561275 and 381, that added together give a palindrome (6561656).

The spelling of 6561275381 in words is "six billion, five hundred sixty-one million, two hundred seventy-five thousand, three hundred eighty-one".