61564140109 has 2 divisors, whose sum is σ = 61564140110. Its totient is φ = 61564140108.

The previous prime is 61564140007. The next prime is 61564140133. The reversal of 61564140109 is 90104146516.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 35127006084 + 26437134025 = 187422^2 + 162595^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-61564140109 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (61564140149) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 30782070054 + 30782070055.

It is an arithmetic number, because the mean of its divisors is an integer number (30782070055).

Almost surely, 2^61564140109 is an apocalyptic number.

It is an amenable number.

61564140109 is a deficient number, since it is larger than the sum of its proper divisors (1).

61564140109 is an equidigital number, since it uses as much as digits as its factorization.

61564140109 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 25920, while the sum is 37.

The spelling of 61564140109 in words is "sixty-one billion, five hundred sixty-four million, one hundred forty thousand, one hundred nine".