1663506181 has 2 divisors, whose sum is σ = 1663506182. Its totient is φ = 1663506180.

The previous prime is 1663506113. The next prime is 1663506193. The reversal of 1663506181 is 1816053661.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 994456225 + 669049956 = 31535^2 + 25866^2 .

It is a cyclic number.

It is not a de Polignac number, because 1663506181 - 2¹³ = 1663497989 is a prime.

It is a super-2 number, since 2×1663506181² = 5534505628450409522, which contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 1663506181.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1663506101) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 831753090 + 831753091.

It is an arithmetic number, because the mean of its divisors is an integer number (831753091).

Almost surely, 2^1663506181 is an apocalyptic number.

It is an amenable number.

1663506181 is a deficient number, since it is larger than the sum of its proper divisors (1).

1663506181 is an equidigital number, since it uses as much as digits as its factorization.

1663506181 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 25920, while the sum is 37.

The square root of 1663506181 is about 40786.1027924954. The cubic root of 1663506181 is about 1184.8811932615.

The spelling of 1663506181 in words is "one billion, six hundred sixty-three million, five hundred six thousand, one hundred eighty-one".