3125899781 has 2 divisors, whose sum is σ = 3125899782. Its totient is φ = 3125899780.

The previous prime is 3125899753. The next prime is 3125899783. The reversal of 3125899781 is 1879985213.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 3098703556 + 27196225 = 55666^2 + 5215^2 .

It is an emirp because it is prime and its reverse (1879985213) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 3125899781 - 2⁶ = 3125899717 is a prime.

It is a super-2 number, since 2×3125899781² = 19542498881711695922, which contains 22 as substring.

Together with 3125899783, it forms a pair of twin primes.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (3125899783) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 1562949890 + 1562949891.

It is an arithmetic number, because the mean of its divisors is an integer number (1562949891).

Almost surely, 2^3125899781 is an apocalyptic number.

It is an amenable number.

3125899781 is a deficient number, since it is larger than the sum of its proper divisors (1).

3125899781 is an equidigital number, since it uses as much as digits as its factorization.

3125899781 is an evil number, because the sum of its binary digits is even.

The product of its digits is 1088640, while the sum is 53.

The square root of 3125899781 is about 55909.7467441948. The cubic root of 3125899781 is about 1462.1491743402.

The spelling of 3125899781 in words is "three billion, one hundred twenty-five million, eight hundred ninety-nine thousand, seven hundred eighty-one".