1671561481 has 4 divisors (see below), whose sum is σ = 1671645700. Its totient is φ = 1671477264.

The previous prime is 1671561473. The next prime is 1671561487. The reversal of 1671561481 is 1841651761.

It is a happy number.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It can be written as a sum of positive squares in 2 ways, for example, as 4064256 + 1667497225 = 2016^2 + 40835^2 .

It is a cyclic number.

It is not a de Polignac number, because 1671561481 - 2³ = 1671561473 is a prime.

It is a super-2 number, since 2×1671561481² = 5588235569525826722, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1671561487) 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, 5935 + ... + 58123.

It is an arithmetic number, because the mean of its divisors is an integer number (417911425).

Almost surely, 2^1671561481 is an apocalyptic number.

It is an amenable number.

1671561481 is a deficient number, since it is larger than the sum of its proper divisors (84219).

1671561481 is an equidigital number, since it uses as much as digits as its factorization.

1671561481 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 84218.

The product of its digits is 40320, while the sum is 40.

The square root of 1671561481 is about 40884.7340825399. The cubic root of 1671561481 is about 1186.7906558977.

The spelling of 1671561481 in words is "one billion, six hundred seventy-one million, five hundred sixty-one thousand, four hundred eighty-one".