661315236523 has 4 divisors (see below), whose sum is σ = 661547851128. Its totient is φ = 661082621920.

The previous prime is 661315236521. The next prime is 661315236529. The reversal of 661315236523 is 325632513166.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 325632513166 = 2 ⋅162816256583.

It is a cyclic number.

It is not a de Polignac number, because 661315236523 - 2¹ = 661315236521 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 661315236523.

It is not an unprimeable number, because it can be changed into a prime (661315236521) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 116303038 + ... + 116308723.

It is an arithmetic number, because the mean of its divisors is an integer number (165386962782).

Almost surely, 2^661315236523 is an apocalyptic number.

661315236523 is a deficient number, since it is larger than the sum of its proper divisors (232614605).

661315236523 is a wasteful number, since it uses less digits than its factorization.

661315236523 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 232614604.

The product of its digits is 583200, while the sum is 43.

Adding to 661315236523 its reverse (325632513166), we get a palindrome (986947749689).

The spelling of 661315236523 in words is "six hundred sixty-one billion, three hundred fifteen million, two hundred thirty-six thousand, five hundred twenty-three".