61539581 has 2 divisors, whose sum is σ = 61539582. Its totient is φ = 61539580.

The previous prime is 61539553. The next prime is 61539587. The reversal of 61539581 is 18593516.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 39062500 + 22477081 = 6250^2 + 4741^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-61539581 is a prime.

It is a super-3 number, since 3×61539581³ (a number of 24 digits) contains 333 as substring. Note that it is a super-d number also for d = 2.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (61539587) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 30769790 + 30769791.

It is an arithmetic number, because the mean of its divisors is an integer number (30769791).

Almost surely, 2^61539581 is an apocalyptic number.

It is an amenable number.

61539581 is a deficient number, since it is larger than the sum of its proper divisors (1).

61539581 is an equidigital number, since it uses as much as digits as its factorization.

61539581 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 32400, while the sum is 38.

The square root of 61539581 is about 7844.7167571557. The cubic root of 61539581 is about 394.8070007316.

It can be divided in two parts, 61 and 539581, that multiplied together give a triangular number (32914441 = T₈₁₁₃).

The spelling of 61539581 in words is "sixty-one million, five hundred thirty-nine thousand, five hundred eighty-one".