125009821 has 4 divisors (see below), whose sum is σ = 126247644. Its totient is φ = 123772000.

The previous prime is 125009747. The next prime is 125009827. The reversal of 125009821 is 128900521.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 106399225 + 18610596 = 10315^2 + 4314^2 .

It is a cyclic number.

It is not a de Polignac number, because 125009821 - 2¹⁹ = 124485533 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 125009821.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (125009827) 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, 618760 + ... + 618961.

It is an arithmetic number, because the mean of its divisors is an integer number (31561911).

Almost surely, 2^125009821 is an apocalyptic number.

It is an amenable number.

125009821 is a deficient number, since it is larger than the sum of its proper divisors (1237823).

125009821 is a wasteful number, since it uses less digits than its factorization.

125009821 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1237822.

The product of its (nonzero) digits is 1440, while the sum is 28.

The square root of 125009821 is about 11180.7790873445. The cubic root of 125009821 is about 500.0130943237.

The spelling of 125009821 in words is "one hundred twenty-five million, nine thousand, eight hundred twenty-one".