661575777 has 8 divisors (see below), whose sum is σ = 883077216. Its totient is φ = 440562432.

The previous prime is 661575767. The next prime is 661575781. The reversal of 661575777 is 777575166.

It is a happy number.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 661575777 - 2¹⁸ = 661313633 is a prime.

It is not an unprimeable number, because it can be changed into a prime (661575727) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 118848 + ... + 124289.

It is an arithmetic number, because the mean of its divisors is an integer number (110384652).

Almost surely, 2^661575777 is an apocalyptic number.

It is an amenable number.

661575777 is a deficient number, since it is larger than the sum of its proper divisors (221501439).

661575777 is a wasteful number, since it uses less digits than its factorization.

661575777 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 244047.

The product of its digits is 2160900, while the sum is 51.

The square root of 661575777 is about 25721.1153918332. The cubic root of 661575777 is about 871.3511295395.

The spelling of 661575777 in words is "six hundred sixty-one million, five hundred seventy-five thousand, seven hundred seventy-seven".