1605630881 has 4 divisors (see below), whose sum is σ = 1608312000. Its totient is φ = 1602949764.

The previous prime is 1605630877. The next prime is 1605630893. The reversal of 1605630881 is 1880365061.

It is a happy number.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also an emirpimes, since its reverse is a distinct semiprime: 1880365061 = 541 ⋅3475721.

It is a cyclic number.

It is not a de Polignac number, because 1605630881 - 2² = 1605630877 is a prime.

It is a super-2 number, since 2×1605630881² = 5156101052041672322, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1665630881) 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, 1339661 + ... + 1340858.

It is an arithmetic number, because the mean of its divisors is an integer number (402078000).

Almost surely, 2^1605630881 is an apocalyptic number.

It is an amenable number.

1605630881 is a deficient number, since it is larger than the sum of its proper divisors (2681119).

1605630881 is an equidigital number, since it uses as much as digits as its factorization.

1605630881 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2681118.

The product of its (nonzero) digits is 34560, while the sum is 38.

The square root of 1605630881 is about 40070.3241938470. The cubic root of 1605630881 is about 1170.9775551806.

The spelling of 1605630881 in words is "one billion, six hundred five million, six hundred thirty thousand, eight hundred eighty-one".