1581648161 has 4 divisors (see below), whose sum is σ = 1587802692. Its totient is φ = 1575493632.

The previous prime is 1581648113. The next prime is 1581648181. The reversal of 1581648161 is 1618461851.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 1618461851 = 229 ⋅7067519.

It can be written as a sum of positive squares in 2 ways, for example, as 1501097536 + 80550625 = 38744^2 + 8975^2 .

It is a cyclic number.

It is not a de Polignac number, because 1581648161 - 2³⁰ = 507906337 is a prime.

It is a super-2 number, since 2×1581648161² = 5003221810389363842, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1581648181) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 3076880 + ... + 3077393.

It is an arithmetic number, because the mean of its divisors is an integer number (396950673).

Almost surely, 2^1581648161 is an apocalyptic number.

It is an amenable number.

1581648161 is a deficient number, since it is larger than the sum of its proper divisors (6154531).

1581648161 is an equidigital number, since it uses as much as digits as its factorization.

1581648161 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6154530.

The product of its digits is 46080, while the sum is 41.

The square root of 1581648161 is about 39769.9404198699. The cubic root of 1581648161 is about 1165.1181300636.

The spelling of 1581648161 in words is "one billion, five hundred eighty-one million, six hundred forty-eight thousand, one hundred sixty-one".