15551609 has 2 divisors, whose sum is σ = 15551610. Its totient is φ = 15551608.

The previous prime is 15551603. The next prime is 15551621. The reversal of 15551609 is 90615551.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 7823209 + 7728400 = 2797^2 + 2780^2 .

It is a cyclic number.

It is not a de Polignac number, because 15551609 - 2²⁰ = 14503033 is a prime.

It is not a weakly prime, because it can be changed into another prime (15551603) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 7775804 + 7775805.

It is an arithmetic number, because the mean of its divisors is an integer number (7775805).

Almost surely, 2^15551609 is an apocalyptic number.

It is an amenable number.

15551609 is a deficient number, since it is larger than the sum of its proper divisors (1).

15551609 is an equidigital number, since it uses as much as digits as its factorization.

15551609 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 6750, while the sum is 32.

The square root of 15551609 is about 3943.5528397626. The cubic root of 15551609 is about 249.6079668949.

The spelling of 15551609 in words is "fifteen million, five hundred fifty-one thousand, six hundred nine".