15561231 has 8 divisors (see below), whose sum is σ = 23712384. Its totient is φ = 8892120.

The previous prime is 15561229. The next prime is 15561251. The reversal of 15561231 is 13216551.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 15561231 - 2¹ = 15561229 is a prime.

It is a super-2 number, since 2×15561231² = 484303820470722, which contains 22 as substring.

It is a Smith number, since the sum of its digits (24) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (15561211) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 370485 + ... + 370526.

It is an arithmetic number, because the mean of its divisors is an integer number (2964048).

Almost surely, 2^15561231 is an apocalyptic number.

15561231 is a deficient number, since it is larger than the sum of its proper divisors (8151153).

15561231 is an equidigital number, since it uses as much as digits as its factorization.

15561231 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 741021.

The product of its digits is 900, while the sum is 24.

The square root of 15561231 is about 3944.7726170212. The cubic root of 15561231 is about 249.6594349391.

Adding to 15561231 its reverse (13216551), we get a palindrome (28777782).

The spelling of 15561231 in words is "fifteen million, five hundred sixty-one thousand, two hundred thirty-one".