1601661181 has 2 divisors, whose sum is σ = 1601661182. Its totient is φ = 1601661180.

The previous prime is 1601661169. The next prime is 1601661233. The reversal of 1601661181 is 1811661061.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 1545276100 + 56385081 = 39310^2 + 7509^2 .

It is a cyclic number.

It is not a de Polignac number, because 1601661181 - 2⁷ = 1601661053 is a prime.

It is a super-2 number, since 2×1601661181² = 5130637077444629522, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1601661101) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 800830590 + 800830591.

It is an arithmetic number, because the mean of its divisors is an integer number (800830591).

Almost surely, 2^1601661181 is an apocalyptic number.

It is an amenable number.

1601661181 is a deficient number, since it is larger than the sum of its proper divisors (1).

1601661181 is an equidigital number, since it uses as much as digits as its factorization.

1601661181 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 1728, while the sum is 31.

The square root of 1601661181 is about 40020.7593756041. The cubic root of 1601661181 is about 1170.0117321735.

The spelling of 1601661181 in words is "one billion, six hundred one million, six hundred sixty-one thousand, one hundred eighty-one".