861291019 has 4 divisors (see below), whose sum is σ = 861378696. Its totient is φ = 861203344.

The previous prime is 861291017. The next prime is 861291037. The reversal of 861291019 is 910192168.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It is a cyclic number.

It is not a de Polignac number, because 861291019 - 2¹ = 861291017 is a prime.

It is a super-2 number, since 2×861291019² = 1483644438820116722, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (861291017) 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 in 3 ways as a sum of consecutive naturals, for example, 26929 + ... + 49474.

It is an arithmetic number, because the mean of its divisors is an integer number (215344674).

Almost surely, 2^861291019 is an apocalyptic number.

861291019 is a deficient number, since it is larger than the sum of its proper divisors (87677).

861291019 is a wasteful number, since it uses less digits than its factorization.

861291019 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 87676.

The product of its (nonzero) digits is 7776, while the sum is 37.

The square root of 861291019 is about 29347.7600337743. The cubic root of 861291019 is about 951.4441632527. Note that the first 3 decimals are identical.

The spelling of 861291019 in words is "eight hundred sixty-one million, two hundred ninety-one thousand, nineteen".