3131131021 has 4 divisors (see below), whose sum is σ = 3131262844. Its totient is φ = 3130999200.

The previous prime is 3131131007. The next prime is 3131131039. The reversal of 3131131021 is 1201311313.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 1201311313 = 1237 ⋅971149.

It can be written as a sum of positive squares in 2 ways, for example, as 1163764996 + 1967366025 = 34114^2 + 44355^2 .

It is a cyclic number.

It is not a de Polignac number, because 3131131021 - 2¹³ = 3131122829 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 3131130986 and 3131131004.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (3131131001) 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, 19290 + ... + 81451.

It is an arithmetic number, because the mean of its divisors is an integer number (782815711).

Almost surely, 2^3131131021 is an apocalyptic number.

It is an amenable number.

3131131021 is a deficient number, since it is larger than the sum of its proper divisors (131823).

3131131021 is a wasteful number, since it uses less digits than its factorization.

3131131021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 131822.

The product of its (nonzero) digits is 54, while the sum is 16.

The square root of 3131131021 is about 55956.5100859587. The cubic root of 3131131021 is about 1462.9643625976.

Adding to 3131131021 its reverse (1201311313), we get a palindrome (4332442334).

The spelling of 3131131021 in words is "three billion, one hundred thirty-one million, one hundred thirty-one thousand, twenty-one".