1663701661 has 2 divisors, whose sum is σ = 1663701662. Its totient is φ = 1663701660.

The previous prime is 1663701631. The next prime is 1663701671. The reversal of 1663701661 is 1661073661.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 1084384900 + 579316761 = 32930^2 + 24069^2 .

It is a cyclic number.

It is not a de Polignac number, because 1663701661 - 2²⁷ = 1529483933 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 1663701661.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1663701631) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 831850830 + 831850831.

It is an arithmetic number, because the mean of its divisors is an integer number (831850831).

Almost surely, 2^1663701661 is an apocalyptic number.

It is an amenable number.

1663701661 is a deficient number, since it is larger than the sum of its proper divisors (1).

1663701661 is an equidigital number, since it uses as much as digits as its factorization.

1663701661 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 27216, while the sum is 37.

The square root of 1663701661 is about 40788.4991265920. The cubic root of 1663701661 is about 1184.9276035696.

The spelling of 1663701661 in words is "one billion, six hundred sixty-three million, seven hundred one thousand, six hundred sixty-one".