61555009 has 2 divisors, whose sum is σ = 61555010. Its totient is φ = 61555008.

The previous prime is 61554991. The next prime is 61555019. The reversal of 61555009 is 90055516.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 52881984 + 8673025 = 7272^2 + 2945^2 .

It is a cyclic number.

It is not a de Polignac number, because 61555009 - 2⁹ = 61554497 is a prime.

It is not a weakly prime, because it can be changed into another prime (61555019) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 30777504 + 30777505.

It is an arithmetic number, because the mean of its divisors is an integer number (30777505).

Almost surely, 2^61555009 is an apocalyptic number.

It is an amenable number.

61555009 is a deficient number, since it is larger than the sum of its proper divisors (1).

61555009 is an equidigital number, since it uses as much as digits as its factorization.

61555009 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 6750, while the sum is 31.

The square root of 61555009 is about 7845.7000325019. The cubic root of 61555009 is about 394.8399907378.

The spelling of 61555009 in words is "sixty-one million, five hundred fifty-five thousand, nine".