6861355897561 has 27 divisors (see below), whose sum is σ = 7688515551997. Its totient is φ = 6118543676960.

The previous prime is 6861355897537. The next prime is 6861355897601. The reversal of 6861355897561 is 1657985531686.

The square root of 6861355897561 is 2619419.

It is a perfect power (a square), and thus also a powerful number.

It can be written as a sum of positive squares in 4 ways, for example, as 4569038775961 + 2292317121600 = 2137531^2 + 1514040^2 .

It is not a de Polignac number, because 6861355897561 - 2²¹ = 6861353800409 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (6861355898561) by changing a digit.

It is a polite number, since it can be written in 26 ways as a sum of consecutive naturals, for example, 1527119031 + ... + 1527123523.

Almost surely, 2^{6861355897561} is an apocalyptic number.

6861355897561 is the 2619419-th square number.

6861355897561 is the 1309710-th centered octagonal number.

It is an amenable number.

6861355897561 is a deficient number, since it is larger than the sum of its proper divisors (827159654436).

6861355897561 is an frugal number, since it uses more digits than its factorization.

6861355897561 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9114 (or 4557 counting only the distinct ones).

The product of its digits is 326592000, while the sum is 70.

The spelling of 6861355897561 in words is "six trillion, eight hundred sixty-one billion, three hundred fifty-five million, eight hundred ninety-seven thousand, five hundred sixty-one".