661309439 has 12 divisors (see below), whose sum is σ = 770662800. Its totient is φ = 565816608.

The previous prime is 661309403. The next prime is 661309457. The reversal of 661309439 is 934903166.

It is not a de Polignac number, because 661309439 - 2²⁸ = 392873983 is a prime.

It is a super-2 number, since 2×661309439² = 874660348220989442, 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 = 661309396 and 661309405.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (661329439) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 16022 + ... + 39740.

It is an arithmetic number, because the mean of its divisors is an integer number (64221900).

Almost surely, 2^661309439 is an apocalyptic number.

661309439 is a deficient number, since it is larger than the sum of its proper divisors (109353361).

661309439 is a wasteful number, since it uses less digits than its factorization.

661309439 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 24302 (or 24295 counting only the distinct ones).

The product of its (nonzero) digits is 104976, while the sum is 41.

The square root of 661309439 is about 25715.9374513161. The cubic root of 661309439 is about 871.2341839705.

The spelling of 661309439 in words is "six hundred sixty-one million, three hundred nine thousand, four hundred thirty-nine".