15551111 has 2 divisors, whose sum is σ = 15551112. Its totient is φ = 15551110.

The previous prime is 15551099. The next prime is 15551131. The reversal of 15551111 is 11115551.

It is an a-pointer prime, because the next prime (15551131) can be obtained adding 15551111 to its sum of digits (20).

It is a weak prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-15551111 is a prime.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (15551131) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 7775555 + 7775556.

It is an arithmetic number, because the mean of its divisors is an integer number (7775556).

Almost surely, 2^15551111 is an apocalyptic number.

15551111 is a deficient number, since it is larger than the sum of its proper divisors (1).

15551111 is an equidigital number, since it uses as much as digits as its factorization.

15551111 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 125, while the sum is 20.

The square root of 15551111 is about 3943.4896982242. The cubic root of 15551111 is about 249.6053025169.

Adding to 15551111 its reverse (11115551), we get a palindrome (26666662).

The spelling of 15551111 in words is "fifteen million, five hundred fifty-one thousand, one hundred eleven".