3125821 has 2 divisors, whose sum is σ = 3125822. Its totient is φ = 3125820.

The previous prime is 3125819. The next prime is 3125831. The reversal of 3125821 is 1285213.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 3080025 + 45796 = 1755^2 + 214^2 .

It is an emirp because it is prime and its reverse (1285213) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 3125821 - 2¹ = 3125819 is a prime.

Together with 3125819, it forms a pair of twin primes.

It is a junction number, because it is equal to n+sod(n) for n = 3125792 and 3125801.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (3125831) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 1562910 + 1562911.

It is an arithmetic number, because the mean of its divisors is an integer number (1562911).

Almost surely, 2^3125821 is an apocalyptic number.

It is an amenable number.

3125821 is a deficient number, since it is larger than the sum of its proper divisors (1).

3125821 is an equidigital number, since it uses as much as digits as its factorization.

3125821 is an evil number, because the sum of its binary digits is even.

The product of its digits is 480, while the sum is 22.

The square root of 3125821 is about 1767.9991515835. Note that the first 3 decimals coincide. The cubic root of 3125821 is about 146.2136890886.

It can be divided in two parts, 31 and 25821, that added together give a palindrome (25852).

The spelling of 3125821 in words is "three million, one hundred twenty-five thousand, eight hundred twenty-one".