861669612561 has 8 divisors (see below), whose sum is σ = 1150410511744. Its totient is φ = 573687560880.

The previous prime is 861669612523. The next prime is 861669612581. The reversal of 861669612561 is 165216966168.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 861669612561 - 2⁶ = 861669612497 is a prime.

It is a super-2 number, since 2×861669612561² (a number of 25 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (861669612581) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 189709225 + ... + 189713766.

It is an arithmetic number, because the mean of its divisors is an integer number (143801313968).

Almost surely, 2^861669612561 is an apocalyptic number.

It is an amenable number.

861669612561 is a deficient number, since it is larger than the sum of its proper divisors (288740899183).

861669612561 is a wasteful number, since it uses less digits than its factorization.

861669612561 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 379423751.

The product of its digits is 5598720, while the sum is 57.

The spelling of 861669612561 in words is "eight hundred sixty-one billion, six hundred sixty-nine million, six hundred twelve thousand, five hundred sixty-one".