125807821 has 2 divisors, whose sum is σ = 125807822. Its totient is φ = 125807820.

The previous prime is 125807813. The next prime is 125807833. The reversal of 125807821 is 128708521.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 81252196 + 44555625 = 9014^2 + 6675^2 .

It is an emirp because it is prime and its reverse (128708521) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 125807821 - 2³ = 125807813 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (125807221) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 62903910 + 62903911.

It is an arithmetic number, because the mean of its divisors is an integer number (62903911).

Almost surely, 2^125807821 is an apocalyptic number.

It is an amenable number.

125807821 is a deficient number, since it is larger than the sum of its proper divisors (1).

125807821 is an equidigital number, since it uses as much as digits as its factorization.

125807821 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 8960, while the sum is 34.

The square root of 125807821 is about 11216.4085606757. The cubic root of 125807821 is about 501.0747826956.

The spelling of 125807821 in words is "one hundred twenty-five million, eight hundred seven thousand, eight hundred twenty-one".