15625121 has 2 divisors, whose sum is σ = 15625122. Its totient is φ = 15625120.

The previous prime is 15625117. The next prime is 15625123. The reversal of 15625121 is 12152651.

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., 13608721 + 2016400 = 3689^2 + 1420^2 .

It is a cyclic number.

It is not a de Polignac number, because 15625121 - 2² = 15625117 is a prime.

It is a Sophie Germain prime.

Together with 15625123, it forms a pair of twin primes.

It is a Chen prime.

It is a Curzon number.

It is not a weakly prime, because it can be changed into another prime (15625123) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 7812560 + 7812561.

It is an arithmetic number, because the mean of its divisors is an integer number (7812561).

Almost surely, 2^15625121 is an apocalyptic number.

It is an amenable number.

15625121 is a deficient number, since it is larger than the sum of its proper divisors (1).

15625121 is an equidigital number, since it uses as much as digits as its factorization.

15625121 is an evil number, because the sum of its binary digits is even.

The product of its digits is 600, while the sum is 23.

The square root of 15625121 is about 3952.8623806047. The cubic root of 15625121 is about 250.0006453317. Note that the first 3 decimals are identical.

Adding to 15625121 its reverse (12152651), we get a palindrome (27777772).

It can be divided in two parts, 15625 and 121, that multiplied together give a square (1890625 = 1375²).

The spelling of 15625121 in words is "fifteen million, six hundred twenty-five thousand, one hundred twenty-one".