661510723 has 4 divisors (see below), whose sum is σ = 661562568. Its totient is φ = 661458880.

The previous prime is 661510721. The next prime is 661510739. The reversal of 661510723 is 327015166.

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, and also an emirpimes, since its reverse is a distinct semiprime: 327015166 = 2 ⋅163507583.

It is a cyclic number.

It is not a de Polignac number, because 661510723 - 2¹ = 661510721 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (661510721) 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 3 ways as a sum of consecutive naturals, for example, 8115 + ... + 37267.

It is an arithmetic number, because the mean of its divisors is an integer number (165390642).

Almost surely, 2^661510723 is an apocalyptic number.

661510723 is a deficient number, since it is larger than the sum of its proper divisors (51845).

661510723 is a wasteful number, since it uses less digits than its factorization.

661510723 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 51844.

The product of its (nonzero) digits is 7560, while the sum is 31.

The square root of 661510723 is about 25719.8507577319. The cubic root of 661510723 is about 871.3225680673.

Adding to 661510723 its reverse (327015166), we get a palindrome (988525889).

The spelling of 661510723 in words is "six hundred sixty-one million, five hundred ten thousand, seven hundred twenty-three".