861551071 has 2 divisors, whose sum is σ = 861551072. Its totient is φ = 861551070.

The previous prime is 861551069. The next prime is 861551077. The reversal of 861551071 is 170155168.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 861551071 - 2¹ = 861551069 is a prime.

Together with 861551069, 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 (861551077) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 430775535 + 430775536.

It is an arithmetic number, because the mean of its divisors is an integer number (430775536).

Almost surely, 2^861551071 is an apocalyptic number.

861551071 is a deficient number, since it is larger than the sum of its proper divisors (1).

861551071 is an equidigital number, since it uses as much as digits as its factorization.

861551071 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 8400, while the sum is 34.

The square root of 861551071 is about 29352.1902249219. The cubic root of 861551071 is about 951.5399110137.

The spelling of 861551071 in words is "eight hundred sixty-one million, five hundred fifty-one thousand, seventy-one".