15625009 has 4 divisors (see below), whose sum is σ = 15957504. Its totient is φ = 15292516.

The previous prime is 15625007. The next prime is 15625013. The reversal of 15625009 is 90052651.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also an emirpimes, since its reverse is a distinct semiprime: 90052651 = 13 ⋅6927127.

It is a cyclic number.

It is not a de Polignac number, because 15625009 - 2¹ = 15625007 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (15625007) 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, 166177 + ... + 166270.

It is an arithmetic number, because the mean of its divisors is an integer number (3989376).

Almost surely, 2^15625009 is an apocalyptic number.

It is an amenable number.

15625009 is a deficient number, since it is larger than the sum of its proper divisors (332495).

15625009 is an equidigital number, since it uses as much as digits as its factorization.

15625009 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 332494.

The product of its (nonzero) digits is 2700, while the sum is 28.

The square root of 15625009 is about 3952.8482136303. The cubic root of 15625009 is about 250.0000480000. Note that the first 4 decimals are identical.

It can be divided in two parts, 1562500 and 9, that multiplied together give a square (14062500 = 3750²).

The spelling of 15625009 in words is "fifteen million, six hundred twenty-five thousand, nine".