1919531561 has 2 divisors, whose sum is σ = 1919531562. Its totient is φ = 1919531560.

The previous prime is 1919531543. The next prime is 1919531573. The reversal of 1919531561 is 1651359191.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 1916775961 + 2755600 = 43781^2 + 1660^2 .

It is a cyclic number.

It is not a de Polignac number, because 1919531561 - 2¹⁴ = 1919515177 is a prime.

It is not a weakly prime, because it can be changed into another prime (1919531531) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 959765780 + 959765781.

It is an arithmetic number, because the mean of its divisors is an integer number (959765781).

Almost surely, 2^1919531561 is an apocalyptic number.

It is an amenable number.

1919531561 is a deficient number, since it is larger than the sum of its proper divisors (1).

1919531561 is an equidigital number, since it uses as much as digits as its factorization.

1919531561 is an evil number, because the sum of its binary digits is even.

The product of its digits is 36450, while the sum is 41.

The square root of 1919531561 is about 43812.4589700236. The cubic root of 1919531561 is about 1242.7919143761.

The spelling of 1919531561 in words is "one billion, nine hundred nineteen million, five hundred thirty-one thousand, five hundred sixty-one".