661686423 has 8 divisors (see below), whose sum is σ = 882849408. Its totient is φ = 440823864.

The previous prime is 661686367. The next prime is 661686449. The reversal of 661686423 is 324686166.

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

It is not a de Polignac number, because 661686423 - 2¹² = 661682327 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (661686323) 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, 69915 + ... + 78812.

It is an arithmetic number, because the mean of its divisors is an integer number (110356176).

Almost surely, 2^661686423 is an apocalyptic number.

661686423 is a deficient number, since it is larger than the sum of its proper divisors (221162985).

661686423 is a wasteful number, since it uses less digits than its factorization.

661686423 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 150213.

The product of its digits is 248832, while the sum is 42.

The square root of 661686423 is about 25723.2661806389. The cubic root of 661686423 is about 871.3997035381.

It can be divided in two parts, 6616 and 86423, that added together give a palindrome (93039).

The spelling of 661686423 in words is "six hundred sixty-one million, six hundred eighty-six thousand, four hundred twenty-three".