661023311 has 4 divisors (see below), whose sum is σ = 711871272. Its totient is φ = 610175352.

The previous prime is 661023301. The next prime is 661023343. The reversal of 661023311 is 113320166.

It is a happy number.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 113320166 = 2 ⋅56660083.

It is a cyclic number.

It is not a de Polignac number, because 661023311 - 2⁶ = 661023247 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 (661023301) 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, 25423961 + ... + 25423986.

It is an arithmetic number, because the mean of its divisors is an integer number (177967818).

Almost surely, 2^661023311 is an apocalyptic number.

661023311 is a deficient number, since it is larger than the sum of its proper divisors (50847961).

661023311 is a wasteful number, since it uses less digits than its factorization.

661023311 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 50847960.

The product of its (nonzero) digits is 648, while the sum is 23.

The square root of 661023311 is about 25710.3736067759. The cubic root of 661023311 is about 871.1085138777.

Adding to 661023311 its reverse (113320166), we get a palindrome (774343477).

The spelling of 661023311 in words is "six hundred sixty-one million, twenty-three thousand, three hundred eleven".