811511551 has 2 divisors, whose sum is σ = 811511552. Its totient is φ = 811511550.

The previous prime is 811511549. The next prime is 811511579. The reversal of 811511551 is 155115118.

It is an a-pointer prime, because the next prime (811511579) can be obtained adding 811511551 to its sum of digits (28).

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 811511551 - 2¹ = 811511549 is a prime.

Together with 811511549, 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 (811511531) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 405755775 + 405755776.

It is an arithmetic number, because the mean of its divisors is an integer number (405755776).

Almost surely, 2^811511551 is an apocalyptic number.

811511551 is a deficient number, since it is larger than the sum of its proper divisors (1).

811511551 is an equidigital number, since it uses as much as digits as its factorization.

811511551 is an evil number, because the sum of its binary digits is even.

The product of its digits is 1000, while the sum is 28.

The square root of 811511551 is about 28487.0418085136. The cubic root of 811511551 is about 932.7492359687.

Adding to 811511551 its reverse (155115118), we get a palindrome (966626669).

The spelling of 811511551 in words is "eight hundred eleven million, five hundred eleven thousand, five hundred fifty-one".