661775967 has 32 divisors (see below), whose sum is σ = 1002792960. Its totient is φ = 431177760.

The previous prime is 661775923. The next prime is 661775971. The reversal of 661775967 is 769577166.

It is a happy number.

It is not a de Polignac number, because 661775967 - 2⁶ = 661775903 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (661775267) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 444298 + ... + 445784.

It is an arithmetic number, because the mean of its divisors is an integer number (31337280).

Almost surely, 2^661775967 is an apocalyptic number.

661775967 is a deficient number, since it is larger than the sum of its proper divisors (341016993).

661775967 is a wasteful number, since it uses less digits than its factorization.

661775967 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1860 (or 1854 counting only the distinct ones).

The product of its digits is 3333960, while the sum is 54.

The square root of 661775967 is about 25725.0066472295. The cubic root of 661775967 is about 871.4390097174.

The spelling of 661775967 in words is "six hundred sixty-one million, seven hundred seventy-five thousand, nine hundred sixty-seven".