1669187561 has 2 divisors, whose sum is σ = 1669187562. Its totient is φ = 1669187560.

The previous prime is 1669187503. The next prime is 1669187567. The reversal of 1669187561 is 1657819661.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 1387115536 + 282072025 = 37244^2 + 16795^2 .

It is a cyclic number.

It is not a de Polignac number, because 1669187561 - 2⁶ = 1669187497 is a prime.

It is a super-2 number, since 2×1669187561² = 5572374227594257442, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (1669187567) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 834593780 + 834593781.

It is an arithmetic number, because the mean of its divisors is an integer number (834593781).

Almost surely, 2^1669187561 is an apocalyptic number.

It is an amenable number.

1669187561 is a deficient number, since it is larger than the sum of its proper divisors (1).

1669187561 is an equidigital number, since it uses as much as digits as its factorization.

1669187561 is an evil number, because the sum of its binary digits is even.

The product of its digits is 544320, while the sum is 50.

The square root of 1669187561 is about 40855.6919045560. The cubic root of 1669187561 is about 1186.2285705116.

The spelling of 1669187561 in words is "one billion, six hundred sixty-nine million, one hundred eighty-seven thousand, five hundred sixty-one".