139540561 has 2 divisors, whose sum is σ = 139540562. Its totient is φ = 139540560.

The previous prime is 139540559. The next prime is 139540567. The reversal of 139540561 is 165045931.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 120670225 + 18870336 = 10985^2 + 4344^2 .

It is a cyclic number.

It is not a de Polignac number, because 139540561 - 2¹ = 139540559 is a prime.

Together with 139540559, it forms a pair of twin primes.

It is not a weakly prime, because it can be changed into another prime (139540567) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 69770280 + 69770281.

It is an arithmetic number, because the mean of its divisors is an integer number (69770281).

Almost surely, 2^139540561 is an apocalyptic number.

It is an amenable number.

139540561 is a deficient number, since it is larger than the sum of its proper divisors (1).

139540561 is an equidigital number, since it uses as much as digits as its factorization.

139540561 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 16200, while the sum is 34.

The square root of 139540561 is about 11812.7287702715. The cubic root of 139540561 is about 518.6807795382.

The spelling of 139540561 in words is "one hundred thirty-nine million, five hundred forty thousand, five hundred sixty-one".