861551069 has 2 divisors, whose sum is σ = 861551070. Its totient is φ = 861551068.

The previous prime is 861551059. The next prime is 861551071. The reversal of 861551069 is 960155168.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 683195044 + 178356025 = 26138^2 + 13355^2 .

It is a cyclic number.

It is not a de Polignac number, because 861551069 - 2²⁰ = 860502493 is a prime.

It is a super-2 number, since 2×861551069² = 1484540488990085522, which contains 22 as substring.

Together with 861551071, it forms a pair of twin primes.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (861551059) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 430775534 + 430775535.

It is an arithmetic number, because the mean of its divisors is an integer number (430775535).

Almost surely, 2^861551069 is an apocalyptic number.

It is an amenable number.

861551069 is a deficient number, since it is larger than the sum of its proper divisors (1).

861551069 is an equidigital number, since it uses as much as digits as its factorization.

861551069 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 64800, while the sum is 41.

The square root of 861551069 is about 29352.1901908529. The cubic root of 861551069 is about 951.5399102774.

The spelling of 861551069 in words is "eight hundred sixty-one million, five hundred fifty-one thousand, sixty-nine".