125513021 has 4 divisors (see below), whose sum is σ = 125593212. Its totient is φ = 125432832.

The previous prime is 125513009. The next prime is 125513029. The reversal of 125513021 is 120315521.

It is a happy number.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 120315521 = 331 ⋅363491.

It can be written as a sum of positive squares in 2 ways, for example, as 40780996 + 84732025 = 6386^2 + 9205^2 .

It is a cyclic number.

It is not a de Polignac number, because 125513021 - 2¹⁸ = 125250877 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 125512984 and 125513002.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (125513029) 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, 37700 + ... + 40893.

It is an arithmetic number, because the mean of its divisors is an integer number (31398303).

Almost surely, 2^125513021 is an apocalyptic number.

It is an amenable number.

125513021 is a deficient number, since it is larger than the sum of its proper divisors (80191).

125513021 is an equidigital number, since it uses as much as digits as its factorization.

125513021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 80190.

The product of its (nonzero) digits is 300, while the sum is 20.

The square root of 125513021 is about 11203.2593918020. The cubic root of 125513021 is about 500.6830943393.

Adding to 125513021 its reverse (120315521), we get a palindrome (245828542).

The spelling of 125513021 in words is "one hundred twenty-five million, five hundred thirteen thousand, twenty-one".