661023331 has 4 divisors (see below), whose sum is σ = 661075272. Its totient is φ = 660971392.

The previous prime is 661023301. The next prime is 661023343. The reversal of 661023331 is 133320166.

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.

It is a cyclic number.

It is not a de Polignac number, because 661023331 - 2¹⁷ = 660892259 is a prime.

It is a super-2 number, since 2×661023331² = 873903688252671122, which contains 22 as substring.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 661023296 and 661023305.

It is not an unprimeable number, because it can be changed into a prime (661023301) 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, 7491 + ... + 37123.

It is an arithmetic number, because the mean of its divisors is an integer number (165268818).

Almost surely, 2^661023331 is an apocalyptic number.

661023331 is a deficient number, since it is larger than the sum of its proper divisors (51941).

661023331 is a wasteful number, since it uses less digits than its factorization.

661023331 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 51940.

The product of its (nonzero) digits is 1944, while the sum is 25.

The square root of 661023331 is about 25710.3739957240. The cubic root of 661023331 is about 871.1085226631.

Adding to 661023331 its reverse (133320166), we get a palindrome (794343497).

The spelling of 661023331 in words is "six hundred sixty-one million, twenty-three thousand, three hundred thirty-one".