76561 has 2 divisors, whose sum is σ = 76562. Its totient is φ = 76560.

The previous prime is 76543. The next prime is 76579. The reversal of 76561 is 16567.

It is a balanced prime because it is at equal distance from previous prime (76543) and next prime (76579).

It can be written as a sum of positive squares in only one way, i.e., 65536 + 11025 = 256^2 + 105^2 .

It is an emirp because it is prime and its reverse (16567) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 76561 - 2¹⁵ = 43793 is a prime.

It is an alternating number because its digits alternate between odd and even.

It is a nialpdrome in base 5.

It is not a weakly prime, because it can be changed into another prime (76511) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 38280 + 38281.

It is an arithmetic number, because the mean of its divisors is an integer number (38281).

2⁷⁶⁵⁶¹ is an apocalyptic number.

It is an amenable number.

76561 is a deficient number, since it is larger than the sum of its proper divisors (1).

76561 is an equidigital number, since it uses as much as digits as its factorization.

76561 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 1260, while the sum is 25.

The square root of 76561 is about 276.6965847277. The cubic root of 76561 is about 42.4622039982.

It can be divided in two parts, 765 and 61, that multiplied together give a triangular number (46665 = T₃₀₅).

The spelling of 76561 in words is "seventy-six thousand, five hundred sixty-one".