661609097 has 4 divisors (see below), whose sum is σ = 662409936. Its totient is φ = 660808260.

The previous prime is 661609093. The next prime is 661609139. The reversal of 661609097 is 790906166.

It is a happy number.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 661609097 - 2² = 661609093 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (661609093) 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, 399179 + ... + 400832.

It is an arithmetic number, because the mean of its divisors is an integer number (165602484).

Almost surely, 2^661609097 is an apocalyptic number.

It is an amenable number.

661609097 is a deficient number, since it is larger than the sum of its proper divisors (800839).

661609097 is an equidigital number, since it uses as much as digits as its factorization.

661609097 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 800838.

The product of its (nonzero) digits is 122472, while the sum is 44.

The square root of 661609097 is about 25721.7631005341. The cubic root of 661609097 is about 871.3657577112.

It can be divided in two parts, 66160 and 9097, that added together give a palindrome (75257).

The spelling of 661609097 in words is "six hundred sixty-one million, six hundred nine thousand, ninety-seven".