11855551 has 2 divisors, whose sum is σ = 11855552. Its totient is φ = 11855550.

The previous prime is 11855549. The next prime is 11855567. The reversal of 11855551 is 15555811.

It is a happy number.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 11855551 - 2¹ = 11855549 is a prime.

Together with 11855549, it forms a pair of twin primes.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (11855521) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 5927775 + 5927776.

It is an arithmetic number, because the mean of its divisors is an integer number (5927776).

Almost surely, 2^11855551 is an apocalyptic number.

11855551 is a deficient number, since it is larger than the sum of its proper divisors (1).

11855551 is an equidigital number, since it uses as much as digits as its factorization.

11855551 is an evil number, because the sum of its binary digits is even.

The product of its digits is 5000, while the sum is 31.

The square root of 11855551 is about 3443.1890740998. The cubic root of 11855551 is about 228.0205108766.

The spelling of 11855551 in words is "eleven million, eight hundred fifty-five thousand, five hundred fifty-one".