61521409 has 2 divisors, whose sum is σ = 61521410. Its totient is φ = 61521408.

The previous prime is 61521403. The next prime is 61521413. The reversal of 61521409 is 90412516.

61521409 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 55130625 + 6390784 = 7425^2 + 2528^2 .

It is a cyclic number.

It is not a de Polignac number, because 61521409 - 2³ = 61521401 is a prime.

It is not a weakly prime, because it can be changed into another prime (61521401) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 30760704 + 30760705.

It is an arithmetic number, because the mean of its divisors is an integer number (30760705).

Almost surely, 2^61521409 is an apocalyptic number.

It is an amenable number.

61521409 is a deficient number, since it is larger than the sum of its proper divisors (1).

61521409 is an equidigital number, since it uses as much as digits as its factorization.

61521409 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 2160, while the sum is 28.

The square root of 61521409 is about 7843.5584398919. The cubic root of 61521409 is about 394.7681361018.

The spelling of 61521409 in words is "sixty-one million, five hundred twenty-one thousand, four hundred nine".