1561969139 has 2 divisors, whose sum is σ = 1561969140. Its totient is φ = 1561969138.

The previous prime is 1561969103. The next prime is 1561969153. The reversal of 1561969139 is 9319691651.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 1561969139 - 2¹² = 1561965043 is a prime.

It is a super-3 number, since 3×1561969139³ (a number of 29 digits) contains 333 as substring.

It is not a weakly prime, because it can be changed into another prime (1561969939) 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, 780984569 + 780984570.

It is an arithmetic number, because the mean of its divisors is an integer number (780984570).

Almost surely, 2^1561969139 is an apocalyptic number.

1561969139 is a deficient number, since it is larger than the sum of its proper divisors (1).

1561969139 is an equidigital number, since it uses as much as digits as its factorization.

1561969139 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 393660, while the sum is 50.

The square root of 1561969139 is about 39521.7552621338. The cubic root of 1561969139 is about 1160.2657781314.

The spelling of 1561969139 in words is "one billion, five hundred sixty-one million, nine hundred sixty-nine thousand, one hundred thirty-nine".