661415623 has 16 divisors (see below), whose sum is σ = 763540992. Its totient is φ = 567028000.

The previous prime is 661415621. The next prime is 661415639. The reversal of 661415623 is 326514166.

It is not a de Polignac number, because 661415623 - 2¹ = 661415621 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (661415621) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 448 + ... + 36373.

It is an arithmetic number, because the mean of its divisors is an integer number (47721312).

Almost surely, 2^661415623 is an apocalyptic number.

661415623 is a deficient number, since it is larger than the sum of its proper divisors (102125369).

661415623 is a wasteful number, since it uses less digits than its factorization.

661415623 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 36926.

The product of its digits is 25920, while the sum is 34.

The square root of 661415623 is about 25718.0019247219. The cubic root of 661415623 is about 871.2808117538.

Adding to 661415623 its reverse (326514166), we get a palindrome (987929789).

The spelling of 661415623 in words is "six hundred sixty-one million, four hundred fifteen thousand, six hundred twenty-three".