3128634781 has 4 divisors (see below), whose sum is σ = 3132446364. Its totient is φ = 3124823200.

The previous prime is 3128634779. The next prime is 3128634827. The reversal of 3128634781 is 1874368213.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 1874368213 = 89 ⋅21060317.

It can be written as a sum of positive squares in 2 ways, for example, as 1438684900 + 1689949881 = 37930^2 + 41109^2 .

It is a cyclic number.

It is not a de Polignac number, because 3128634781 - 2¹ = 3128634779 is a prime.

It is a super-2 number, since 2×3128634781² = 19576711185765835922, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (3128634181) 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, 1904560 + ... + 1906201.

It is an arithmetic number, because the mean of its divisors is an integer number (783111591).

Almost surely, 2^3128634781 is an apocalyptic number.

It is an amenable number.

3128634781 is a deficient number, since it is larger than the sum of its proper divisors (3811583).

3128634781 is an equidigital number, since it uses as much as digits as its factorization.

3128634781 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3811582.

The product of its digits is 193536, while the sum is 43.

The square root of 3128634781 is about 55934.2004591109. The cubic root of 3128634781 is about 1462.5754849002.

The spelling of 3128634781 in words is "three billion, one hundred twenty-eight million, six hundred thirty-four thousand, seven hundred eighty-one".